docs: Downgrade Next.js (#12408)

### Description

Having some build problems after a Next.js upgrade.

Author: anthonyshew

apps/docs/next-env.d.ts

@@ -1,6 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-import "./.next/types/routes.d.ts";
+import "./.next/dev/types/routes.d.ts";
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.

apps/docs/package.json

@@ -49,7 +49,7 @@
     "lucide-react": "^0.555.0",
     "motion": "^12.23.25",
     "nanoid": "^5.1.6",
-    "next": "16.1.7",
+    "next": "16.1.5",
     "next-themes": "^0.4.6",
     "radix-ui": "latest",
     "react": "^19.2.3",