build(deps): bump react from 19.2.5 to 19.2.6 in /frontend

Bumps [react](https://github.com/facebook/react/tree/HEAD/packages/react) from 19.2.5 to 19.2.6.
- [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/v19.2.6/packages/react)

---
updated-dependencies:
- dependency-name: react
  dependency-version: 19.2.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

frontend/package.json

@@ -52,7 +52,7 @@
     "lucide-react": "^0.454.0",
     "next": "^16.1.6",
     "next-themes": "^0.4.6",
-    "react": "^19.2.5",
+    "react": "^19.2.6",
     "react-day-picker": "^9.14.0",
     "react-dom": "^19.1.0",
     "react-hook-form": "^7.75.0",