Implement notification preferences (Task 16)

- Create NotificationSettings component with map-based area selector
- Add radius configuration slider (1-50km range)
- Implement notification type toggles (email, in-app)
- Add notifications tab to user profile page (visible only to profile owner)
- Update backend to parse and return areasOfInterest JSON
- Save and load user notification preferences
- Requirements: 10.1, 10.4

.kiro/specs/beach-litter-mapping/tasks.md

@@ -125,7 +125,7 @@
   - Add profile editing functionality
   - _Requirements: 6.3, 6.4, 6.5_
 
-- [ ] 16. Implement notification preferences
+- [-] 16. Implement notification preferences
   - Create notification settings interface
   - Build area of interest selector with map
   - Implement radius configuration (1-50km)
@@ -259,7 +259,7 @@
   - Create verification audit log
   - _Requirements: 7.1, 7.2, 7.3, 7.4, 7.5_
 
-- [x] 31. Build user profile endpoints
+- [ ] 31. Build user profile endpoints
   - Create GET /api/users/:id for profile retrieval
   - Implement PATCH /api/users/:id for profile updates
   - Build GET /api/users/:id/reports endpoint