chore(deps): bump react from 18.3.1 to 19.2.4 in /frontend

Bumps [react](https://github.com/facebook/react/tree/HEAD/packages/react) from 18.3.1 to 19.2.4.
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/main/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/v19.2.4/packages/react)

---
updated-dependencies:
- dependency-name: react
  dependency-version: 19.2.4
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

frontend/package.json

@@ -32,7 +32,7 @@
     "framer-motion": "^12.29.0",
     "lucide-react": "^0.554.0",
     "next-themes": "^0.4.6",
-    "react": "^18.2.0",
+    "react": "^19.2.4",
     "react-dom": "^18.2.0",
     "react-router-dom": "^7.12.0",
     "react-syntax-highlighter": "^16.1.0",