feat: implement notification system with Mailgun email integration

- Add notifications table with migration
- Create NotificationService with area-of-interest matching
- Integrate Mailgun for email delivery
- Add notification API endpoints (get, mark as read, unread count)
- Create scheduled jobs for event reminders and cleanup
- Build NotificationBell component for frontend
- Add notification triggers for reports and events
- Implement comprehensive test script
- Update Header with notification bell
- Add email templates with HTML formatting

Requirements satisfied:
- 10.1: Users can define areas of interest (1-50km radius)
- 10.2: Notifications sent within 10 minutes
- 10.3: Notifications for new reports/events in user area
- 10.4: Configurable notification preferences (email/in-app)

Task 33 completed

server/package.json

@@ -28,8 +28,10 @@
     "exifr": "^7.1.3",
     "express": "^4.21.1",
     "express-validator": "^7.2.0",
+    "form-data": "^4.0.4",
     "helmet": "^8.0.0",
     "json2csv": "^6.0.0-alpha.2",
+    "mailgun.js": "^12.1.1",
     "multer": "^1.4.5-lts.1",
     "node-cron": "^4.2.1",
     "redis": "^5.9.0",