Update nextjs monorepo to v16

Author: renovate[bot]

package.json

@@ -10,7 +10,7 @@
   },
   "dependencies": {
     "markdown-to-jsx": "^7.4.7",
-    "next": "15.5.6",
+    "next": "16.0.6",
     "react": "^18.3.1",
     "react-dom": "^18.3.1"
   },
@@ -21,7 +21,7 @@
     "contentful-import": "^9.4.39",
     "dotenv": "^17.0.0",
     "eslint": "^8.57.1",
-    "eslint-config-next": "^15.0.0",
+    "eslint-config-next": "^16.0.0",
     "postcss": "^8.5.1",
     "tailwindcss": "^4.0.0"
   }