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/component/src/components/not-found-page/not-found-page.tsx

@@ -1,5 +1,6 @@
 import { useI18n } from '@affine/i18n';
 import { SignOutIcon } from '@blocksuite/icons/rc';
+import type { JSX } from 'react';
 
 import { Avatar } from '../../ui/avatar';
 import { Button, IconButton } from '../../ui/button';