Add Vocabulary Learning Platform (Phase 1: DB + API + Editor)

Strategic pivot: Studio-v2 becomes a language learning platform.
Compliance guardrail added to CLAUDE.md — no scan/OCR of third-party
content in customer frontend. Upload of OWN materials remains allowed.

Phase 1.1 — vocabulary_db.py: PostgreSQL model for 160k+ words
with english, german, IPA, syllables, examples, images, audio,
difficulty, tags, translations (multilingual). Trigram search index.

Phase 1.2 — vocabulary_api.py: Search, browse, filters, bulk import,
learning unit creation from word selection. Creates QA items with
enhanced fields (IPA, syllables, image, audio) for flashcards.

Phase 1.3 — /vocabulary page: Search bar with POS/difficulty filters,
word cards with audio buttons, unit builder sidebar. Teacher selects
words → creates learning unit → redirects to flashcards.

Sidebar: Added "Woerterbuch" (/vocabulary) and "Lernmodule" (/learn).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

studio-v2/app/vocabulary/page.tsx

@@ -0,0 +1,319 @@
+'use client'
+
+import React, { useState, useEffect, useCallback } from 'react'
+import { useRouter } from 'next/navigation'
+import { useTheme } from '@/lib/ThemeContext'
+import { Sidebar } from '@/components/Sidebar'
+import { AudioButton } from '@/components/learn/AudioButton'
+
+interface VocabWord {
+  id: string
+  english: string
+  german: string
+  ipa_en: string
+  ipa_de: string
+  part_of_speech: string
+  syllables_en: string[]
+  syllables_de: string[]
+  example_en: string
+  example_de: string
+  image_url: string
+  difficulty: number
+  tags: string[]
+}
+
+function getBackendUrl() {
+  if (typeof window === 'undefined') return 'http://localhost:8001'
+  const { hostname, protocol } = window.location
+  if (hostname === 'localhost') return 'http://localhost:8001'
+  return `${protocol}//${hostname}:8001`
+}
+
+export default function VocabularyPage() {
+  const { isDark } = useTheme()
+  const router = useRouter()
+
+  const [query, setQuery] = useState('')
+  const [results, setResults] = useState<VocabWord[]>([])
+  const [isSearching, setIsSearching] = useState(false)
+  const [filters, setFilters] = useState<{ tags: string[]; parts_of_speech: string[]; total_words: number }>({ tags: [], parts_of_speech: [], total_words: 0 })
+  const [posFilter, setPosFilter] = useState('')
+  const [diffFilter, setDiffFilter] = useState(0)
+
+  // Unit builder
+  const [selectedWords, setSelectedWords] = useState<VocabWord[]>([])
+  const [unitTitle, setUnitTitle] = useState('')
+  const [isCreating, setIsCreating] = useState(false)
+
+  const glassCard = isDark
+    ? 'bg-white/10 backdrop-blur-xl border border-white/10'
+    : 'bg-white/80 backdrop-blur-xl border border-black/5'
+
+  const glassInput = isDark
+    ? 'bg-white/10 border-white/20 text-white placeholder-white/40'
+    : 'bg-white border-slate-200 text-slate-900 placeholder-slate-400'
+
+  // Load filters on mount
+  useEffect(() => {
+    fetch(`${getBackendUrl()}/api/vocabulary/filters`)
+      .then(r => r.ok ? r.json() : null)
+      .then(d => { if (d) setFilters(d) })
+      .catch(() => {})
+  }, [])
+
+  // Search with debounce
+  useEffect(() => {
+    if (!query.trim() && !posFilter && !diffFilter) {
+      setResults([])
+      return
+    }
+
+    const timer = setTimeout(async () => {
+      setIsSearching(true)
+      try {
+        let url: string
+        if (query.trim()) {
+          url = `${getBackendUrl()}/api/vocabulary/search?q=${encodeURIComponent(query)}&limit=30`
+        } else {
+          const params = new URLSearchParams({ limit: '30' })
+          if (posFilter) params.set('pos', posFilter)
+          if (diffFilter) params.set('difficulty', String(diffFilter))
+          url = `${getBackendUrl()}/api/vocabulary/browse?${params}`
+        }
+        const resp = await fetch(url)
+        if (resp.ok) {
+          const data = await resp.json()
+          setResults(data.words || [])
+        }
+      } catch (err) {
+        console.error('Search failed:', err)
+      } finally {
+        setIsSearching(false)
+      }
+    }, 300)
+
+    return () => clearTimeout(timer)
+  }, [query, posFilter, diffFilter])
+
+  const toggleWord = useCallback((word: VocabWord) => {
+    setSelectedWords(prev => {
+      const exists = prev.find(w => w.id === word.id)
+      if (exists) return prev.filter(w => w.id !== word.id)
+      return [...prev, word]
+    })
+  }, [])
+
+  const createUnit = useCallback(async () => {
+    if (!unitTitle.trim() || selectedWords.length === 0) return
+    setIsCreating(true)
+    try {
+      const resp = await fetch(`${getBackendUrl()}/api/vocabulary/units`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({
+          title: unitTitle,
+          word_ids: selectedWords.map(w => w.id),
+        }),
+      })
+      if (resp.ok) {
+        const data = await resp.json()
+        router.push(`/learn/${data.unit_id}/flashcards`)
+      }
+    } catch (err) {
+      console.error('Create unit failed:', err)
+    } finally {
+      setIsCreating(false)
+    }
+  }, [unitTitle, selectedWords, router])
+
+  const isSelected = (wordId: string) => selectedWords.some(w => w.id === wordId)
+
+  return (
+    <div className={`min-h-screen flex relative overflow-hidden ${
+      isDark ? 'bg-gradient-to-br from-indigo-900 via-purple-900 to-pink-800' : 'bg-gradient-to-br from-slate-100 via-blue-50 to-cyan-100'
+    }`}>
+      <div className="relative z-10 p-4"><Sidebar /></div>
+
+      <div className="flex-1 flex flex-col relative z-10 overflow-y-auto">
+        {/* Header */}
+        <div className={`${glassCard} border-0 border-b`}>
+          <div className="max-w-5xl mx-auto px-6 py-4">
+            <div className="flex items-center gap-4">
+              <div className={`w-12 h-12 rounded-xl flex items-center justify-center ${isDark ? 'bg-blue-500/30' : 'bg-blue-200'}`}>
+                <svg className={`w-6 h-6 ${isDark ? 'text-blue-300' : 'text-blue-600'}`} fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M12 6.253v13m0-13C10.832 5.477 9.246 5 7.5 5S4.168 5.477 3 6.253v13C4.168 18.477 5.754 18 7.5 18s3.332.477 4.5 1.253m0-13C13.168 5.477 14.754 5 16.5 5c1.747 0 3.332.477 4.5 1.253v13C19.832 18.477 18.247 18 16.5 18c-1.746 0-3.332.477-4.5 1.253" />
+                </svg>
+              </div>
+              <div>
+                <h1 className={`text-xl font-bold ${isDark ? 'text-white' : 'text-slate-900'}`}>Woerterbuch</h1>
+                <p className={`text-sm ${isDark ? 'text-white/60' : 'text-slate-500'}`}>
+                  {filters.total_words > 0 ? `${filters.total_words.toLocaleString()} Woerter` : 'Woerter suchen und Lernunits erstellen'}
+                </p>
+              </div>
+            </div>
+          </div>
+        </div>
+
+        <div className="max-w-5xl mx-auto w-full px-6 py-6 flex gap-6">
+          {/* Left: Search + Results */}
+          <div className="flex-1 space-y-4">
+            {/* Search Bar */}
+            <div className={`${glassCard} rounded-2xl p-4`}>
+              <div className="flex gap-3">
+                <input
+                  type="text"
+                  value={query}
+                  onChange={e => setQuery(e.target.value)}
+                  placeholder="Wort suchen (EN oder DE)..."
+                  className={`flex-1 px-4 py-3 rounded-xl border outline-none text-lg ${glassInput}`}
+                  autoFocus
+                />
+                <select value={posFilter} onChange={e => setPosFilter(e.target.value)}
+                  className={`px-3 py-2 rounded-xl border text-sm ${glassInput}`}>
+                  <option value="">Alle Wortarten</option>
+                  {filters.parts_of_speech.map(p => <option key={p} value={p}>{p}</option>)}
+                </select>
+                <select value={diffFilter} onChange={e => setDiffFilter(Number(e.target.value))}
+                  className={`px-3 py-2 rounded-xl border text-sm ${glassInput}`}>
+                  <option value={0}>Alle Level</option>
+                  <option value={1}>A1</option>
+                  <option value={2}>A2</option>
+                  <option value={3}>B1</option>
+                  <option value={4}>B2</option>
+                  <option value={5}>C1</option>
+                </select>
+              </div>
+            </div>
+
+            {/* Results */}
+            {isSearching && (
+              <div className="flex justify-center py-8">
+                <div className={`w-6 h-6 border-2 ${isDark ? 'border-blue-400' : 'border-blue-600'} border-t-transparent rounded-full animate-spin`} />
+              </div>
+            )}
+
+            {!isSearching && results.length === 0 && query.trim() && (
+              <div className={`${glassCard} rounded-2xl p-8 text-center`}>
+                <p className={isDark ? 'text-white/50' : 'text-slate-500'}>Keine Ergebnisse fuer &quot;{query}&quot;</p>
+              </div>
+            )}
+
+            <div className="space-y-2">
+              {results.map(word => (
+                <div
+                  key={word.id}
+                  className={`${glassCard} rounded-xl p-4 flex items-center gap-4 transition-all cursor-pointer ${
+                    isSelected(word.id)
+                      ? (isDark ? 'ring-2 ring-blue-400/50 bg-blue-500/10' : 'ring-2 ring-blue-500/50 bg-blue-50')
+                      : 'hover:shadow-md'
+                  }`}
+                  onClick={() => toggleWord(word)}
+                >
+                  {/* Image or emoji placeholder */}
+                  <div className={`w-14 h-14 rounded-xl flex items-center justify-center text-2xl flex-shrink-0 ${isDark ? 'bg-white/5' : 'bg-slate-100'}`}>
+                    {word.image_url ? (
+                      <img src={word.image_url} alt={word.english} className="w-full h-full object-cover rounded-xl" />
+                    ) : (
+                      <span className="text-xl">📝</span>
+                    )}
+                  </div>
+
+                  {/* Word info */}
+                  <div className="flex-1 min-w-0">
+                    <div className="flex items-center gap-2">
+                      <span className={`font-bold text-lg ${isDark ? 'text-white' : 'text-slate-900'}`}>{word.english}</span>
+                      {word.ipa_en && <span className={`text-sm ${isDark ? 'text-white/40' : 'text-slate-400'}`}>{word.ipa_en}</span>}
+                      <AudioButton text={word.english} lang="en" isDark={isDark} size="sm" />
+                    </div>
+                    <div className="flex items-center gap-2">
+                      <span className={`${isDark ? 'text-white/70' : 'text-slate-600'}`}>{word.german}</span>
+                      <AudioButton text={word.german} lang="de" isDark={isDark} size="sm" />
+                    </div>
+                    <div className="flex items-center gap-2 mt-1">
+                      {word.part_of_speech && (
+                        <span className={`text-xs px-2 py-0.5 rounded-full ${isDark ? 'bg-purple-500/20 text-purple-300' : 'bg-purple-100 text-purple-700'}`}>
+                          {word.part_of_speech}
+                        </span>
+                      )}
+                      {word.syllables_en.length > 0 && (
+                        <span className={`text-xs ${isDark ? 'text-white/30' : 'text-slate-400'}`}>
+                          {word.syllables_en.join(' · ')}
+                        </span>
+                      )}
+                    </div>
+                  </div>
+
+                  {/* Select indicator */}
+                  <div className={`w-8 h-8 rounded-full flex items-center justify-center flex-shrink-0 transition-colors ${
+                    isSelected(word.id)
+                      ? 'bg-blue-500 text-white'
+                      : isDark ? 'bg-white/10 text-white/30' : 'bg-slate-100 text-slate-300'
+                  }`}>
+                    <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                      <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2.5} d={isSelected(word.id) ? "M5 13l4 4L19 7" : "M12 4v16m8-8H4"} />
+                    </svg>
+                  </div>
+                </div>
+              ))}
+            </div>
+          </div>
+
+          {/* Right: Unit Builder */}
+          <div className="w-80 flex-shrink-0">
+            <div className={`${glassCard} rounded-2xl p-5 sticky top-6`}>
+              <h3 className={`text-lg font-semibold mb-3 ${isDark ? 'text-white' : 'text-slate-900'}`}>
+                Lernunit erstellen
+              </h3>
+
+              <input
+                type="text"
+                value={unitTitle}
+                onChange={e => setUnitTitle(e.target.value)}
+                placeholder="Titel (z.B. Unit 3 - Food)"
+                className={`w-full px-4 py-2.5 rounded-xl border outline-none text-sm mb-4 ${glassInput}`}
+              />
+
+              {selectedWords.length === 0 ? (
+                <p className={`text-sm text-center py-6 ${isDark ? 'text-white/40' : 'text-slate-400'}`}>
+                  Klicke auf Woerter um sie hinzuzufuegen
+                </p>
+              ) : (
+                <div className="space-y-1.5 max-h-80 overflow-y-auto mb-4">
+                  {selectedWords.map((w, i) => (
+                    <div key={w.id} className={`flex items-center justify-between px-3 py-2 rounded-lg ${isDark ? 'bg-white/5' : 'bg-slate-50'}`}>
+                      <div className="flex items-center gap-2 min-w-0">
+                        <span className={`text-xs w-5 text-center ${isDark ? 'text-white/30' : 'text-slate-400'}`}>{i+1}</span>
+                        <span className={`text-sm font-medium truncate ${isDark ? 'text-white' : 'text-slate-900'}`}>{w.english}</span>
+                        <span className={`text-xs truncate ${isDark ? 'text-white/40' : 'text-slate-400'}`}>{w.german}</span>
+                      </div>
+                      <button onClick={(e) => { e.stopPropagation(); toggleWord(w) }}
+                        className={`text-xs ${isDark ? 'text-red-400 hover:text-red-300' : 'text-red-500 hover:text-red-700'}`}>
+                        ✕
+                      </button>
+                    </div>
+                  ))}
+                </div>
+              )}
+
+              <div className={`text-xs mb-3 ${isDark ? 'text-white/40' : 'text-slate-400'}`}>
+                {selectedWords.length} Woerter ausgewaehlt
+              </div>
+
+              <button
+                onClick={createUnit}
+                disabled={isCreating || selectedWords.length === 0 || !unitTitle.trim()}
+                className={`w-full py-3 rounded-xl font-medium transition-all ${
+                  selectedWords.length > 0 && unitTitle.trim()
+                    ? 'bg-gradient-to-r from-blue-500 to-cyan-500 text-white hover:shadow-lg'
+                    : isDark ? 'bg-white/5 text-white/30' : 'bg-slate-100 text-slate-400'
+                }`}
+              >
+                {isCreating ? 'Wird erstellt...' : 'Lernunit starten'}
+              </button>
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  )
+}