feat: add real-time collaboration features with STOMP and SockJS

- Added @stomp/stompjs and sockjs-client dependencies for WebSocket communication.
- Updated routing for pastes to include new endpoint structure.
- Implemented real-time editing in PastePanel using STOMP for collaborative editing.
- Introduced NotificationModal for experimental mode warnings.
- Enhanced NavBar to display connection status.
- Refactored Home and PastePanel components to support new features and improve user experience.
- Updated error handling in DataContext to utilize ErrorContext for better error management.
- Added CSS animations for connection status indication.

package.json

@@ -16,6 +16,7 @@
     "@fortawesome/free-solid-svg-icons": "^7.0.0",
     "@fortawesome/react-fontawesome": "^0.2.3",
     "@monaco-editor/react": "^4.7.0",
+    "@stomp/stompjs": "^7.3.0",
     "axios": "^1.11.0",
     "bootstrap": "^5.3.7",
     "date-fns": "^4.1.0",
@@ -26,7 +27,8 @@
     "react-dom": "^19.1.0",
     "react-router-dom": "^7.7.1",
     "react-slick": "^0.30.3",
-    "slick-carousel": "^1.8.1"
+    "slick-carousel": "^1.8.1",
+    "sockjs-client": "^1.6.1"
   },
   "devDependencies": {
     "@eslint/js": "^9.30.1",