update next.js to v16

package.json

@@ -15,7 +15,7 @@
     "@mdx-js/loader": "^3.1.1",
     "@mdx-js/react": "^3.1.1",
     "@next-auth/mongodb-adapter": "^1.1.3",
-    "@next/mdx": "^15.3.9",
+    "@next/mdx": "^16.1.6",
     "@types/mdx": "^2.0.11",
     "@vercel/analytics": "^1.6.1",
     "autoprefixer": "^10.4.24",
@@ -24,7 +24,7 @@
     "googleapis": "^148.0.0",
     "ics": "^3.8.1",
     "mongoose": "^9.1.5",
-    "next": "^15.3.9",
+    "next": "^16.1.6",
     "next-auth": "^4.24.13",
     "next-axiom": "^1.10.0",
     "nodemailer": "^7.0.13",
@@ -36,7 +36,7 @@
     "@tailwindcss/postcss": "^4.1.18",
     "@types/nodemailer": "^6.4.17",
     "eslint": "^9.39.2",
-    "eslint-config-next": "^15.3.9",
+    "eslint-config-next": "^16.1.6",
     "eslint-config-prettier": "^10.1.8",
     "jest": "^29.7.0",
     "postcss": "^8.5.6",