web(vercel): remove install/build commands; project is deployed with prebuilt build/web via CI, avoid Vercel attempting npm install in output dir

Author: aimuhire

mobile/vercel.json

@@ -5,7 +5,5 @@
     { "handle": "filesystem" },
     { "src": "/(.*)", "dest": "/index.html" }
   ],
-  "buildCommand": "npm run build",
-  "installCommand": "npm install",
   "framework": null
 }