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/session/cleanup_job.py

@@ -0,0 +1,141 @@
+"""
+Session Cleanup Job
+
+Removes expired sessions from PostgreSQL.
+Valkey handles its own expiry via TTL.
+
+This job should be run periodically (e.g., via cron or APScheduler).
+
+Usage:
+    # Run directly
+    python -m session.cleanup_job
+
+    # Or import and call
+    from session.cleanup_job import run_cleanup
+
+    await run_cleanup()
+"""
+
+import asyncio
+import logging
+import os
+from datetime import datetime, timezone
+
+logger = logging.getLogger(__name__)
+
+
+async def run_cleanup():
+    """Run session cleanup job."""
+    from .session_store import get_session_store
+
+    logger.info("Starting session cleanup job...")
+
+    try:
+        store = await get_session_store()
+        count = await store.cleanup_expired_sessions()
+        logger.info(f"Session cleanup completed: removed {count} expired sessions")
+        return count
+    except Exception as e:
+        logger.error(f"Session cleanup failed: {e}")
+        raise
+
+
+async def run_cleanup_with_pg():
+    """
+    Run cleanup directly with PostgreSQL connection.
+
+    Useful when session store is not initialized.
+    """
+    database_url = os.environ.get("DATABASE_URL")
+    if not database_url:
+        logger.warning("DATABASE_URL not set, skipping cleanup")
+        return 0
+
+    try:
+        import asyncpg
+
+        conn = await asyncpg.connect(database_url)
+        try:
+            # Delete sessions expired more than 7 days ago
+            result = await conn.execute("""
+                DELETE FROM user_sessions
+                WHERE expires_at < NOW() - INTERVAL '7 days'
+            """)
+            count = int(result.split()[-1]) if result else 0
+            logger.info(f"Session cleanup completed: removed {count} expired sessions")
+            return count
+        finally:
+            await conn.close()
+    except Exception as e:
+        logger.error(f"Session cleanup failed: {e}")
+        return 0
+
+
+def setup_scheduler():
+    """
+    Setup APScheduler for periodic cleanup.
+
+    Runs cleanup every 6 hours.
+    """
+    try:
+        from apscheduler.schedulers.asyncio import AsyncIOScheduler
+        from apscheduler.triggers.interval import IntervalTrigger
+
+        scheduler = AsyncIOScheduler()
+
+        scheduler.add_job(
+            run_cleanup,
+            trigger=IntervalTrigger(hours=6),
+            id="session_cleanup",
+            name="Session Cleanup Job",
+            replace_existing=True,
+        )
+
+        scheduler.start()
+        logger.info("Session cleanup scheduler started (runs every 6 hours)")
+
+        return scheduler
+
+    except ImportError:
+        logger.warning("APScheduler not installed, cleanup job not scheduled")
+        return None
+
+
+def register_with_fastapi(app):
+    """
+    Register cleanup job with FastAPI app lifecycle.
+
+    Usage:
+        from session.cleanup_job import register_with_fastapi
+        register_with_fastapi(app)
+    """
+    from contextlib import asynccontextmanager
+
+    scheduler = None
+
+    @asynccontextmanager
+    async def lifespan(app):
+        nonlocal scheduler
+        # Startup
+        scheduler = setup_scheduler()
+        # Run initial cleanup
+        asyncio.create_task(run_cleanup())
+
+        yield
+
+        # Shutdown
+        if scheduler:
+            scheduler.shutdown()
+
+    return lifespan
+
+
+if __name__ == "__main__":
+    # Configure logging
+    logging.basicConfig(
+        level=logging.INFO,
+        format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+    )
+
+    # Run cleanup
+    asyncio.run(run_cleanup_with_pg())