fix(deps): update nextjs monorepo to v16

Author: renovate[bot]

package.json

@@ -26,8 +26,8 @@
     "@types/react": "19.2.2",
     "@types/react-dom": "19.2.2",
     "eslint": "9.38.0",
-    "eslint-config-next": "15.5.6",
-    "next": "15.5.6",
+    "eslint-config-next": "16.0.0",
+    "next": "16.0.0",
     "next-auth": "^4.24.7",
     "react": "19.2.0",
     "react-dom": "19.2.0",