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/notifications.py

@@ -0,0 +1,57 @@
+import uuid
+from typing import Annotated
+
+from fastapi import APIRouter, Depends, Query, status
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.api.deps import get_current_user
+from app.database import get_db
+from app.models.user import User
+from app.schemas.notification import NotificationListResponse, NotificationResponse, UnreadCountResponse
+from app.services import notification_service
+
+router = APIRouter(prefix="/notifications", tags=["notifications"])
+
+
+@router.get("/", response_model=NotificationListResponse)
+async def list_notifications(
+    user: Annotated[User, Depends(get_current_user)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+    status_filter: str | None = Query(default=None, alias="status"),
+    limit: int = Query(default=50, le=200),
+    offset: int = Query(default=0),
+):
+    notifications = await notification_service.get_user_notifications(db, user.id, status_filter, limit, offset)
+    unread = await notification_service.get_unread_count(db, user.id)
+    return NotificationListResponse(
+        notifications=[NotificationResponse.model_validate(n) for n in notifications],
+        unread_count=unread,
+    )
+
+
+@router.get("/unread-count", response_model=UnreadCountResponse)
+async def unread_count(
+    user: Annotated[User, Depends(get_current_user)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    count = await notification_service.get_unread_count(db, user.id)
+    return UnreadCountResponse(count=count)
+
+
+@router.patch("/{notification_id}/read", response_model=NotificationResponse)
+async def mark_read(
+    notification_id: uuid.UUID,
+    user: Annotated[User, Depends(get_current_user)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    notif = await notification_service.mark_as_read(db, notification_id, user.id)
+    return NotificationResponse.model_validate(notif)
+
+
+@router.post("/mark-all-read", status_code=status.HTTP_200_OK)
+async def mark_all_read(
+    user: Annotated[User, Depends(get_current_user)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    count = await notification_service.mark_all_read(db, user.id)
+    return {"marked": count}