Implement real-time notifications with WebSocket

[fadee26]

Summary

This PR implements real-time notifications using WebSockets, allowing users to receive instant updates on critical events without refreshing the page.

Changes Made

Backend

1. Database Model: Added Notification model to persist notifications (user_id, type, title, message, is_read, reference_id, created_at, updated_at)
2. Schemas: Created Pydantic schemas for notification creation/response
3. API Endpoints:
   • GET /notifications/ - Fetch user's notifications
   • GET /notifications/unread-count - Get unread notification count
   • PUT /notifications/{id}/read - Mark single notification as read
   • PUT /notifications/mark-all-read - Mark all notifications as read
   • DELETE /notifications/{id} - Delete notification
   • WS /notifications/ws - WebSocket endpoint for real-time updates
4. WebSocket Manager: Added ConnectionManager to handle active WebSocket connections
5. Notification Integration:
   • Added notifications on booking status changes (confirmed, canceled, started, completed)
   • Added notifications on payment release and refund

Frontend

1. NotificationContext: Updated to use WebSocket instead of polling, and added toast alerts
2. NotificationBell: Updated to handle clicking notifications (mark as read + navigate)
3. Toast Provider: Already integrated to show real-time alerts

How to Test

1. Run the backend and apply the migration
2. Log in as both a client and an artisan (separate browsers)
3. Create a booking as a client, then accept it as the artisan - both users should receive notifications
4. Complete the booking and release payment - both users should receive notifications

Next Steps

• Add more notification types (e.g., new bids, disputes)
• Add notification preferences (users can choose which events to be notified about)
• Add email/SMS notifications as fallback

closes #298

[fadee26]

@ohamamarachi474-del
@gabito1451
please approve workflow