Phase 5: Notifications — WebSocket, APScheduler, AI tool, health review

Backend:
- Notification model + Alembic migration
- Notification service: CRUD, mark read, unread count, pending scheduled
- WebSocket manager singleton for real-time push
- WebSocket endpoint /ws/notifications with JWT auth via query param
- APScheduler integration: periodic notification sender (every 60s),
  daily proactive health review job (8 AM)
- AI tool: schedule_notification (immediate or scheduled)
- Health review worker: analyzes user memory via Claude, creates
  ai_generated notifications with WebSocket push

Frontend:
- Notification API client + Zustand store
- WebSocket hook with auto-reconnect (exponential backoff)
- Notification bell in header with unread count badge + dropdown
- Notifications page with type badges, mark read, mark all read
- WebSocket initialized in AppLayout for app-wide real-time updates
- Enabled notifications nav in sidebar
- English + Russian translations

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/api/v1/router.py

@@ -7,6 +7,8 @@ from app.api.v1.skills import router as skills_router
 from app.api.v1.users import router as users_router
 from app.api.v1.documents import router as documents_router
 from app.api.v1.memory import router as memory_router
+from app.api.v1.notifications import router as notifications_router
+from app.api.v1.ws import router as ws_router
 
 api_v1_router = APIRouter(prefix="/api/v1")
 
@@ -17,6 +19,8 @@ api_v1_router.include_router(skills_router)
 api_v1_router.include_router(users_router)
 api_v1_router.include_router(documents_router)
 api_v1_router.include_router(memory_router)
+api_v1_router.include_router(notifications_router)
+api_v1_router.include_router(ws_router)
 
 
 @api_v1_router.get("/health")