Bump next from 16.2.4 to 16.2.6 in /frontend

Bumps [next](https://github.com/vercel/next.js) from 16.2.4 to 16.2.6.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v16.2.4...v16.2.6)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 16.2.6
  dependency-type: direct:production
...

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

Author: dependabot[bot]

frontend/package-lock.json

@@ -34,7 +34,7 @@
     "eslint-plugin-react": "^7.37.5",
     "eslint-plugin-simple-import-sort": "^13.0.0",
     "lucide-react": "^1.14.0",
-    "next": "16.2.4",
+    "next": "16.2.6",
     "next-auth": "^4.24.14",
     "next-themes": "^0.4.6",
     "postcss": "^8.5.14",