fix(core): add null checks for timeout refs and event listeners for React 19 compatibility (#9116)

## Description
- Add null checks before clearTimeout calls in colorful-fallback.tsx, edgeless.dialog.tsx, and local.dialog.tsx
- Fix event listener cleanup in unfolding.tsx
- Update tsconfig.jsx to use react-jsx transform

## Testing
- [x] Verified type safety improvements for React 19 compatibility
- [x] Ensured proper cleanup of event listeners and timeouts
- [x] Confirmed no unintended side effects from the changes

Link to Devin run: https://app.devin.ai/sessions/2e790f3ea0d84402837ec6c3c6f83e4c

packages/frontend/i18n/package.json

@@ -20,7 +20,7 @@
     "@magic-works/i18n-codegen": "^0.6.0",
     "dayjs": "^1.11.11",
     "i18next": "^24.0.0",
-    "react": "^18.2.0",
+    "react": "^19.0.0",
     "react-i18next": "^15.0.0",
     "undici": "^7.0.0"
   },