fix: Restore all files lost during destructive rebase

A previous `git pull --rebase origin main` dropped 177 local commits,
losing 3400+ files across admin-v2, backend, studio-v2, website,
klausur-service, and many other services. The partial restore attempt
(660295e2) only recovered some files.

This commit restores all missing files from pre-rebase ref 98933f5e
while preserving post-rebase additions (night-scheduler, night-mode UI,
NightModeWidget dashboard integration).

Restored features include:
- AI Module Sidebar (FAB), OCR Labeling, OCR Compare
- GPU Dashboard, RAG Pipeline, Magic Help
- Klausur-Korrektur (8 files), Abitur-Archiv (5+ files)
- Companion, Zeugnisse-Crawler, Screen Flow
- Full backend, studio-v2, website, klausur-service
- All compliance SDKs, agent-core, voice-service
- CI/CD configs, documentation, scripts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin-v2/components/companion/ModeToggle.tsx

@@ -0,0 +1,61 @@
+'use client'
+
+import { GraduationCap, Timer, Layout } from 'lucide-react'
+import { CompanionMode } from '@/lib/companion/types'
+
+interface ModeToggleProps {
+  currentMode: CompanionMode
+  onModeChange: (mode: CompanionMode) => void
+  disabled?: boolean
+}
+
+const modes: { id: CompanionMode; label: string; icon: React.ReactNode; description: string }[] = [
+  {
+    id: 'companion',
+    label: 'Companion',
+    icon: <GraduationCap className="w-4 h-4" />,
+    description: 'Dashboard mit Vorschlaegen',
+  },
+  {
+    id: 'lesson',
+    label: 'Lesson',
+    icon: <Timer className="w-4 h-4" />,
+    description: 'Timer und Phasen',
+  },
+  {
+    id: 'classic',
+    label: 'Classic',
+    icon: <Layout className="w-4 h-4" />,
+    description: 'Klassische Ansicht',
+  },
+]
+
+export function ModeToggle({ currentMode, onModeChange, disabled }: ModeToggleProps) {
+  return (
+    <div className="bg-white border border-slate-200 rounded-xl p-1 inline-flex gap-1">
+      {modes.map((mode) => {
+        const isActive = currentMode === mode.id
+        return (
+          <button
+            key={mode.id}
+            onClick={() => onModeChange(mode.id)}
+            disabled={disabled}
+            className={`
+              flex items-center gap-2 px-4 py-2 rounded-lg text-sm font-medium
+              transition-all duration-200
+              ${isActive
+                ? 'bg-slate-900 text-white shadow-sm'
+                : 'text-slate-600 hover:bg-slate-100 hover:text-slate-900'
+              }
+              ${disabled ? 'opacity-50 cursor-not-allowed' : 'cursor-pointer'}
+            `}
+            title={mode.description}
+          >
+            {mode.icon}
+            <span>{mode.label}</span>
+          </button>
+        )
+      })}
+    </div>
+  )
+}