fix: add Vercel configuration for proper Next.js deployment

Added vercel.json to explicitly configure:
- Framework as nextjs
- Build command with proper pnpm script
- Output directory as .next

This ensures Vercel correctly deploys the Next.js application
instead of serving static files only.

Author: wbfossadmin

vercel.json

@@ -0,0 +1,6 @@
+{
+  "framework": "nextjs",
+  "buildCommand": "pnpm run build",
+  "installCommand": "pnpm install",
+  "outputDirectory": ".next"
+}