chore: update configuration for Vercel deployment

- Added postinstall script to rebuild lightningcss for Vercel environment.
- Updated vercel.json to include installCommand, nodeVersion, environment variables, and function runtime settings.

Author: 0xdevcollins

vercel.json

@@ -3,7 +3,6 @@
   "buildCommand": "npm run build",
   "installCommand": "npm install && npm rebuild lightningcss",
   "framework": "nextjs",
-  "nodeVersion": "24.x",
   "env": {
     "npm_config_platform": "linux",
     "npm_config_arch": "x64",