fix(example): update nextjs example dependencies to latest versions (#313)

Update next.js from 12.x to 16.x, React from 18.x to 19.x,
ESLint from 8.x to 9.x, and Vercel CLI from 25.x to 41.x.
This fixes the CI build failure caused by Vercel CLI 25.x not
supporting Node.js 22+.

Author: amondnet

example/nextjs/package.json

@@ -7,13 +7,13 @@
     "lint": "next lint"
   },
   "dependencies": {
-    "next": "12.1.4",
-    "react": "18.0.0",
-    "react-dom": "18.0.0",
-    "vercel": "^25.0.1"
+    "next": "16.2.1",
+    "react": "19.2.4",
+    "react-dom": "19.2.4",
+    "vercel": "^41.1.4"
   },
   "devDependencies": {
-    "eslint": "8.12.0",
-    "eslint-config-next": "12.1.4"
+    "eslint": "9.34.0",
+    "eslint-config-next": "16.2.1"
   }
 }