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>

klausur-service/frontend/src/hooks/useKlausur.tsx

@@ -0,0 +1,175 @@
+import { createContext, useContext, useState, useCallback, ReactNode } from 'react'
+import { klausurApi, Klausur, StudentKlausur } from '../services/api'
+
+interface KlausurContextType {
+  klausuren: Klausur[]
+  currentKlausur: Klausur | null
+  currentStudent: StudentKlausur | null
+  loading: boolean
+  error: string | null
+  loadKlausuren: () => Promise<void>
+  selectKlausur: (id: string, keepStudent?: boolean) => Promise<void>
+  selectStudent: (id: string) => void
+  setStudentById: (id: string) => void
+  refreshAndSelectStudent: (klausurId: string, studentId: string) => Promise<void>
+  createKlausur: (data: Partial<Klausur>) => Promise<Klausur>
+  deleteKlausur: (id: string) => Promise<void>
+  updateCriteria: (studentId: string, criterion: string, score: number) => Promise<void>
+}
+
+const KlausurContext = createContext<KlausurContextType | null>(null)
+
+export function KlausurProvider({ children }: { children: ReactNode }) {
+  const [klausuren, setKlausuren] = useState<Klausur[]>([])
+  const [currentKlausur, setCurrentKlausur] = useState<Klausur | null>(null)
+  const [currentStudent, setCurrentStudent] = useState<StudentKlausur | null>(null)
+  const [loading, setLoading] = useState(false)
+  const [error, setError] = useState<string | null>(null)
+
+  const loadKlausuren = useCallback(async () => {
+    setLoading(true)
+    setError(null)
+    try {
+      const data = await klausurApi.listKlausuren()
+      setKlausuren(data)
+    } catch (e) {
+      setError(e instanceof Error ? e.message : 'Failed to load Klausuren')
+    } finally {
+      setLoading(false)
+    }
+  }, [])
+
+  const selectKlausur = useCallback(async (id: string, keepStudent = false) => {
+    setLoading(true)
+    setError(null)
+    try {
+      const klausur = await klausurApi.getKlausur(id)
+      setCurrentKlausur(klausur)
+      // Optionally keep the current student selection (for refresh after save)
+      if (keepStudent && currentStudent) {
+        const updatedStudent = klausur.students.find(s => s.id === currentStudent.id)
+        setCurrentStudent(updatedStudent || null)
+      } else if (!keepStudent) {
+        setCurrentStudent(null)
+      }
+    } catch (e) {
+      setError(e instanceof Error ? e.message : 'Failed to load Klausur')
+    } finally {
+      setLoading(false)
+    }
+  }, [currentStudent])
+
+  const selectStudent = useCallback((id: string) => {
+    if (!currentKlausur) return
+    const student = currentKlausur.students.find(s => s.id === id)
+    setCurrentStudent(student || null)
+  }, [currentKlausur])
+
+  // Set student directly by ID (for cases where we need to set before state updates)
+  const setStudentById = useCallback((id: string) => {
+    if (!currentKlausur) return
+    const student = currentKlausur.students.find(s => s.id === id)
+    if (student) {
+      setCurrentStudent(student)
+    }
+  }, [currentKlausur])
+
+  // Combined refresh and select - useful after upload
+  const refreshAndSelectStudent = useCallback(async (klausurId: string, studentId: string) => {
+    setLoading(true)
+    setError(null)
+    try {
+      const klausur = await klausurApi.getKlausur(klausurId)
+      setCurrentKlausur(klausur)
+      const student = klausur.students.find(s => s.id === studentId)
+      if (student) {
+        setCurrentStudent(student)
+      }
+    } catch (e) {
+      setError(e instanceof Error ? e.message : 'Failed to load Klausur')
+    } finally {
+      setLoading(false)
+    }
+  }, [])
+
+  const createKlausur = useCallback(async (data: Partial<Klausur>) => {
+    setLoading(true)
+    setError(null)
+    try {
+      const klausur = await klausurApi.createKlausur(data)
+      setKlausuren(prev => [...prev, klausur])
+      return klausur
+    } catch (e) {
+      setError(e instanceof Error ? e.message : 'Failed to create Klausur')
+      throw e
+    } finally {
+      setLoading(false)
+    }
+  }, [])
+
+  const deleteKlausur = useCallback(async (id: string) => {
+    setLoading(true)
+    setError(null)
+    try {
+      await klausurApi.deleteKlausur(id)
+      setKlausuren(prev => prev.filter(k => k.id !== id))
+      if (currentKlausur?.id === id) {
+        setCurrentKlausur(null)
+        setCurrentStudent(null)
+      }
+    } catch (e) {
+      setError(e instanceof Error ? e.message : 'Failed to delete Klausur')
+      throw e
+    } finally {
+      setLoading(false)
+    }
+  }, [currentKlausur])
+
+  const updateCriteria = useCallback(async (studentId: string, criterion: string, score: number) => {
+    try {
+      const updated = await klausurApi.updateCriteria(studentId, criterion, score)
+      if (currentKlausur) {
+        setCurrentKlausur({
+          ...currentKlausur,
+          students: currentKlausur.students.map(s =>
+            s.id === studentId ? updated : s
+          )
+        })
+      }
+      if (currentStudent?.id === studentId) {
+        setCurrentStudent(updated)
+      }
+    } catch (e) {
+      setError(e instanceof Error ? e.message : 'Failed to update criteria')
+      throw e
+    }
+  }, [currentKlausur, currentStudent])
+
+  return (
+    <KlausurContext.Provider value={{
+      klausuren,
+      currentKlausur,
+      currentStudent,
+      loading,
+      error,
+      loadKlausuren,
+      selectKlausur,
+      selectStudent,
+      setStudentById,
+      refreshAndSelectStudent,
+      createKlausur,
+      deleteKlausur,
+      updateCriteria
+    }}>
+      {children}
+    </KlausurContext.Provider>
+  )
+}
+
+export function useKlausur() {
+  const context = useContext(KlausurContext)
+  if (!context) {
+    throw new Error('useKlausur must be used within a KlausurProvider')
+  }
+  return context
+}