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>

backend/api/classroom/settings.py

@@ -0,0 +1,201 @@
+"""
+Classroom API - Settings Endpoints.
+
+Endpoints fuer Lehrer-Einstellungen.
+"""
+
+from typing import Dict, Optional, Any
+from datetime import datetime
+import logging
+
+from fastapi import APIRouter, HTTPException, Query
+from pydantic import BaseModel, Field
+
+from classroom_engine import get_default_durations
+
+from .shared import init_db_if_needed, DB_ENABLED, logger
+
+try:
+    from classroom_engine.database import SessionLocal
+    from classroom_engine.repository import TeacherSettingsRepository
+except ImportError:
+    pass
+
+router = APIRouter(tags=["Settings"])
+
+# In-Memory Storage (Fallback)
+_settings: Dict[str, dict] = {}
+
+
+# === Pydantic Models ===
+
+class PhaseDurationsUpdate(BaseModel):
+    """Update fuer Phasendauern."""
+    einstieg: Optional[int] = Field(None, ge=1, le=30)
+    erarbeitung: Optional[int] = Field(None, ge=5, le=45)
+    sicherung: Optional[int] = Field(None, ge=3, le=20)
+    transfer: Optional[int] = Field(None, ge=3, le=20)
+    reflexion: Optional[int] = Field(None, ge=2, le=15)
+
+
+class PreferencesUpdate(BaseModel):
+    """Update fuer Lehrer-Praeferenzen."""
+    auto_advance: Optional[bool] = None
+    sound_enabled: Optional[bool] = None
+    notification_enabled: Optional[bool] = None
+    theme: Optional[str] = None
+    language: Optional[str] = None
+
+
+class TeacherSettingsResponse(BaseModel):
+    """Response fuer Lehrer-Einstellungen."""
+    teacher_id: str
+    phase_durations: Dict[str, int]
+    preferences: Dict[str, Any]
+    created_at: str
+    updated_at: Optional[str]
+
+
+# === Helper Functions ===
+
+def get_default_settings(teacher_id: str) -> dict:
+    """Gibt die Default-Einstellungen zurueck."""
+    return {
+        "teacher_id": teacher_id,
+        "phase_durations": get_default_durations(),
+        "preferences": {
+            "auto_advance": False,
+            "sound_enabled": True,
+            "notification_enabled": True,
+            "theme": "light",
+            "language": "de",
+        },
+        "created_at": datetime.utcnow().isoformat(),
+        "updated_at": None,
+    }
+
+
+# === Endpoints ===
+
+@router.get("/settings/{teacher_id}", response_model=TeacherSettingsResponse)
+async def get_teacher_settings(teacher_id: str) -> TeacherSettingsResponse:
+    """Ruft die Einstellungen eines Lehrers ab."""
+    init_db_if_needed()
+
+    # Aus Memory pruefen
+    if teacher_id in _settings:
+        return TeacherSettingsResponse(**_settings[teacher_id])
+
+    # Aus DB laden
+    if DB_ENABLED:
+        try:
+            db = SessionLocal()
+            repo = TeacherSettingsRepository(db)
+            db_settings = repo.get_by_teacher(teacher_id)
+            db.close()
+
+            if db_settings:
+                settings_data = repo.to_dict(db_settings)
+                _settings[teacher_id] = settings_data
+                return TeacherSettingsResponse(**settings_data)
+        except Exception as e:
+            logger.warning(f"DB read failed for settings: {e}")
+
+    # Default-Einstellungen erstellen
+    settings_data = get_default_settings(teacher_id)
+    _settings[teacher_id] = settings_data
+
+    if DB_ENABLED:
+        try:
+            db = SessionLocal()
+            repo = TeacherSettingsRepository(db)
+            repo.create(settings_data)
+            db.close()
+        except Exception as e:
+            logger.warning(f"DB persist failed for settings: {e}")
+
+    return TeacherSettingsResponse(**settings_data)
+
+
+@router.put("/settings/{teacher_id}/durations", response_model=TeacherSettingsResponse)
+async def update_phase_durations(
+    teacher_id: str,
+    request: PhaseDurationsUpdate
+) -> TeacherSettingsResponse:
+    """Aktualisiert die Phasendauern eines Lehrers."""
+    init_db_if_needed()
+
+    # Aktuelle Einstellungen laden
+    current = await get_teacher_settings(teacher_id)
+    settings_data = _settings.get(teacher_id, get_default_settings(teacher_id))
+
+    # Nur uebergebene Werte aktualisieren
+    durations = settings_data["phase_durations"]
+    if request.einstieg is not None:
+        durations["einstieg"] = request.einstieg
+    if request.erarbeitung is not None:
+        durations["erarbeitung"] = request.erarbeitung
+    if request.sicherung is not None:
+        durations["sicherung"] = request.sicherung
+    if request.transfer is not None:
+        durations["transfer"] = request.transfer
+    if request.reflexion is not None:
+        durations["reflexion"] = request.reflexion
+
+    settings_data["phase_durations"] = durations
+    settings_data["updated_at"] = datetime.utcnow().isoformat()
+
+    # In DB speichern
+    if DB_ENABLED:
+        try:
+            db = SessionLocal()
+            repo = TeacherSettingsRepository(db)
+            repo.update_durations(teacher_id, durations)
+            db.close()
+        except Exception as e:
+            logger.warning(f"DB update failed for durations: {e}")
+
+    _settings[teacher_id] = settings_data
+    return TeacherSettingsResponse(**settings_data)
+
+
+@router.put("/settings/{teacher_id}/preferences", response_model=TeacherSettingsResponse)
+async def update_preferences(
+    teacher_id: str,
+    request: PreferencesUpdate
+) -> TeacherSettingsResponse:
+    """Aktualisiert die Praeferenzen eines Lehrers."""
+    init_db_if_needed()
+
+    # Aktuelle Einstellungen laden
+    current = await get_teacher_settings(teacher_id)
+    settings_data = _settings.get(teacher_id, get_default_settings(teacher_id))
+
+    # Nur uebergebene Werte aktualisieren
+    prefs = settings_data["preferences"]
+    if request.auto_advance is not None:
+        prefs["auto_advance"] = request.auto_advance
+    if request.sound_enabled is not None:
+        prefs["sound_enabled"] = request.sound_enabled
+    if request.notification_enabled is not None:
+        prefs["notification_enabled"] = request.notification_enabled
+    if request.theme is not None:
+        prefs["theme"] = request.theme
+    if request.language is not None:
+        prefs["language"] = request.language
+
+    settings_data["preferences"] = prefs
+    settings_data["updated_at"] = datetime.utcnow().isoformat()
+
+    # In DB speichern
+    if DB_ENABLED:
+        try:
+            db = SessionLocal()
+            repo = TeacherSettingsRepository(db)
+            repo.update_preferences(teacher_id, prefs)
+            db.close()
+        except Exception as e:
+            logger.warning(f"DB update failed for preferences: {e}")
+
+    _settings[teacher_id] = settings_data
+    return TeacherSettingsResponse(**settings_data)