Implement comprehensive error handling

- Add try-catch blocks to all server actions with retry logic
- Implement exponential backoff retry mechanism for database operations
- Add input validation to all server actions
- Create ErrorBoundary component for React error handling
- Add page-level error handlers (error.tsx, global-error.tsx)
- Add route-specific error pages for list and item routes
- Enhance database connection with graceful error handling
- Add user-friendly error messages throughout the application
- Implement proper error logging for debugging

Task: 16. Implement error handling
Requirements: All (error handling is cross-cutting)

.kiro/specs/ultimate-lists-app/tasks.md

@@ -199,7 +199,7 @@
   - Implement skeleton loaders
   - _Requirements: 7.3_
 
-- [ ] 16. Implement error handling
+- [-] 16. Implement error handling
   - Add try-catch blocks to all server actions
   - Implement error boundaries in React components
   - Add user-friendly error messages