Bump eslint-config-next from 16.2.4 to 16.2.6 in /frontend

Bumps [eslint-config-next](https://github.com/vercel/next.js/tree/HEAD/packages/eslint-config-next) 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](https://github.com/vercel/next.js/commits/v16.2.6/packages/eslint-config-next)

---
updated-dependencies:
- dependency-name: eslint-config-next
  dependency-version: 16.2.6
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

frontend/package-lock.json

@@ -29,7 +29,7 @@
     "@types/react": "^19",
     "@types/react-dom": "^19",
     "eslint": "^10.3.0",
-    "eslint-config-next": "16.2.4",
+    "eslint-config-next": "16.2.6",
     "jsdom": "^29.1.1",
     "tailwindcss": "^4",
     "typescript": "^6",