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/__init__.py

@@ -0,0 +1,52 @@
+"""
+Session Management Module for BreakPilot
+
+Hybrid session storage using Valkey (Redis-fork) for fast lookups
+and PostgreSQL for persistence and DSGVO audit trail.
+
+Components:
+- session_store.py: Hybrid Valkey + PostgreSQL session storage
+- session_middleware.py: FastAPI middleware for session-based auth
+- rbac_middleware.py: User type and permission checking
+"""
+
+from .session_store import (
+    SessionStore,
+    Session,
+    UserType,
+    get_session_store,
+)
+from .session_middleware import (
+    get_current_session,
+    require_session,
+    session_middleware,
+)
+from .rbac_middleware import (
+    require_user_type,
+    require_permission,
+    require_any_permission,
+    require_employee,
+    require_customer,
+    EMPLOYEE_PERMISSIONS,
+    CUSTOMER_PERMISSIONS,
+)
+
+__all__ = [
+    # Session Store
+    "SessionStore",
+    "Session",
+    "UserType",
+    "get_session_store",
+    # Session Middleware
+    "get_current_session",
+    "require_session",
+    "session_middleware",
+    # RBAC Middleware
+    "require_user_type",
+    "require_permission",
+    "require_any_permission",
+    "require_employee",
+    "require_customer",
+    "EMPLOYEE_PERMISSIONS",
+    "CUSTOMER_PERMISSIONS",
+]