chore(deps): bump next from 16.1.7 to 16.2.1 in /frontend

Bumps [next](https://github.com/vercel/next.js) from 16.1.7 to 16.2.1.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](https://github.com/vercel/next.js/compare/v16.1.7...v16.2.1)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 16.2.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

frontend/package.json

@@ -14,7 +14,7 @@
     "@tanstack/react-query": "^5.95.0",
     "axios": "^1.13.6",
     "lucide-react": "^0.577.0",
-    "next": "16.1.7",
+    "next": "16.2.1",
     "react": "19.2.4",
     "react-dom": "19.2.4",
     "zustand": "^5.0.12"