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/utility.py

@@ -0,0 +1,185 @@
+"""
+Classroom API - Utility Endpoints.
+
+Health-Check, Phasen-Liste und andere Utility-Endpoints.
+"""
+
+from typing import Dict, List, Optional, Any
+from datetime import datetime
+import logging
+
+from fastapi import APIRouter, HTTPException, Query
+from fastapi.responses import HTMLResponse
+from sqlalchemy import text
+from pydantic import BaseModel
+
+from classroom_engine import LESSON_PHASES, LessonStateMachine
+
+from .shared import (
+    init_db_if_needed,
+    get_sessions,
+    get_session_or_404,
+    ws_manager,
+    DB_ENABLED,
+    logger,
+)
+
+try:
+    from classroom_engine.database import SessionLocal
+except ImportError:
+    pass
+
+router = APIRouter(tags=["Utility"])
+
+
+# === Pydantic Models ===
+
+class PhasesListResponse(BaseModel):
+    """Liste aller verfuegbaren Phasen."""
+    phases: List[Dict[str, Any]]
+
+
+class ActiveSessionsResponse(BaseModel):
+    """Liste aktiver Sessions."""
+    sessions: List[Dict[str, Any]]
+    count: int
+
+
+# === Endpoints ===
+
+@router.get("/phases", response_model=PhasesListResponse)
+async def list_phases() -> PhasesListResponse:
+    """Listet alle verfuegbaren Unterrichtsphasen mit Metadaten."""
+    phases = []
+    for phase_id, config in LESSON_PHASES.items():
+        phases.append({
+            "phase": phase_id,
+            "display_name": config["display_name"],
+            "default_duration_minutes": config["default_duration_minutes"],
+            "activities": config["activities"],
+            "icon": config["icon"],
+            "description": config.get("description", ""),
+        })
+    return PhasesListResponse(phases=phases)
+
+
+@router.get("/sessions", response_model=ActiveSessionsResponse)
+async def list_active_sessions(
+    teacher_id: Optional[str] = Query(None)
+) -> ActiveSessionsResponse:
+    """Listet alle (optionally gefilterten) Sessions."""
+    sessions = get_sessions()
+    sessions_list = []
+
+    for session in sessions.values():
+        if teacher_id and session.teacher_id != teacher_id:
+            continue
+
+        fsm = LessonStateMachine()
+        sessions_list.append({
+            "session_id": session.session_id,
+            "teacher_id": session.teacher_id,
+            "class_id": session.class_id,
+            "subject": session.subject,
+            "current_phase": session.current_phase.value,
+            "is_active": fsm.is_lesson_active(session),
+            "lesson_started_at": session.lesson_started_at.isoformat() if session.lesson_started_at else None,
+        })
+
+    return ActiveSessionsResponse(sessions=sessions_list, count=len(sessions_list))
+
+
+@router.get("/health")
+async def health_check() -> Dict[str, Any]:
+    """Health-Check fuer den Classroom Service."""
+    db_status = "disabled"
+    if DB_ENABLED:
+        try:
+            db = SessionLocal()
+            db.execute(text("SELECT 1"))
+            db.close()
+            db_status = "connected"
+        except Exception as e:
+            db_status = f"error: {str(e)}"
+
+    sessions = get_sessions()
+    return {
+        "status": "healthy",
+        "service": "classroom-engine",
+        "active_sessions": len(sessions),
+        "db_enabled": DB_ENABLED,
+        "db_status": db_status,
+        "websocket_connections": sum(
+            ws_manager.get_client_count(sid) for sid in ws_manager.get_active_sessions()
+        ),
+        "timestamp": datetime.utcnow().isoformat(),
+    }
+
+
+@router.get("/ws/status")
+async def websocket_status() -> Dict[str, Any]:
+    """Status der WebSocket-Verbindungen."""
+    active_sessions = ws_manager.get_active_sessions()
+    session_counts = {
+        sid: ws_manager.get_client_count(sid) for sid in active_sessions
+    }
+
+    return {
+        "active_sessions": len(active_sessions),
+        "session_connections": session_counts,
+        "total_connections": sum(session_counts.values()),
+        "timestamp": datetime.utcnow().isoformat(),
+    }
+
+
+@router.get("/export/session/{session_id}", response_class=HTMLResponse)
+async def export_session_html(session_id: str) -> HTMLResponse:
+    """Exportiert eine Session als HTML-Dokument."""
+    session = get_session_or_404(session_id)
+
+    # Einfacher HTML-Export
+    html = f"""
+    <!DOCTYPE html>
+    <html lang="de">
+    <head>
+        <meta charset="UTF-8">
+        <title>Session Export - {session.subject}</title>
+        <style>
+            body {{ font-family: Arial, sans-serif; max-width: 800px; margin: 0 auto; padding: 20px; }}
+            h1 {{ color: #333; }}
+            .meta {{ color: #666; margin-bottom: 20px; }}
+            .section {{ margin: 20px 0; padding: 15px; background: #f5f5f5; border-radius: 8px; }}
+            .phase {{ display: flex; justify-content: space-between; padding: 10px 0; border-bottom: 1px solid #ddd; }}
+        </style>
+    </head>
+    <body>
+        <h1>{session.subject}: {session.topic or 'Ohne Thema'}</h1>
+        <div class="meta">
+            <p>Klasse: {session.class_id}</p>
+            <p>Datum: {session.lesson_started_at.strftime('%d.%m.%Y %H:%M') if session.lesson_started_at else 'Nicht gestartet'}</p>
+            <p>Status: {session.current_phase.value}</p>
+        </div>
+
+        <div class="section">
+            <h2>Phasen</h2>
+            {"".join(f'<div class="phase"><span>{p.get("phase", "")}</span><span>{p.get("duration_seconds", 0) // 60} min</span></div>' for p in session.phase_history)}
+        </div>
+
+        <div class="section">
+            <h2>Notizen</h2>
+            <p>{session.notes or 'Keine Notizen'}</p>
+        </div>
+
+        <div class="section">
+            <h2>Hausaufgaben</h2>
+            <p>{session.homework or 'Keine Hausaufgaben'}</p>
+        </div>
+
+        <footer style="margin-top: 40px; color: #999; font-size: 12px;">
+            Exportiert am {datetime.utcnow().strftime('%d.%m.%Y %H:%M')} UTC - BreakPilot Classroom
+        </footer>
+    </body>
+    </html>
+    """
+
+    return HTMLResponse(content=html)