- Remove hardcoded <script> and <link> tags for sweetalert2 from index.html
(library is already bundled via npm, CDN paths caused 404 + MIME errors)
- Remove deprecated 'exact' prop and 'activeClassName' from NavLink in
Navbar.js and NavbarUpload.js (not supported in React Router v6)
- Replace activeClassName with className={({ isActive }) => ...} pattern
- Add future flags to <BrowserRouter> in App.js:
v7_startTransition and v7_relativeSplatPath to suppress RR v6 warnings
- Add ErrorBoundary component for React error handling
- Create animated error pages (403, 404, 500, 502, 503)
- Implement ErrorAnimation component with seven-segment display
- Add apiClient (axios) and apiFetch (fetch) wrappers with automatic error page redirects
- Migrate critical API calls to use new error handling
- Update font from Roboto to Open Sans across all components
- Remove unused CLIENT_URL from docker-compose files
- Rename 404Page.css to ErrorPage.css for consistency
- Add comprehensive ERROR_HANDLING.md documentation
