Fix Vercel deployment issues and add configuration files

- Update .vercelignore to include electron-api.d.ts for build
- Add vercel.json with proper React SPA configuration
- Add .nvmrc for Node.js version specification

Author: pankaj-bind

frontend/.nvmrc

@@ -0,0 +1 @@
+20

frontend/.vercelignore

@@ -13,7 +13,6 @@
 # Electron files
 main.js
 preload.js
-electron-api.d.ts
 
 # Build cache
 .cache

frontend/vercel.json

@@ -1,21 +1,23 @@
 {
-  "framework": "create-react-app",
-  "buildCommand": "npm run build",
+  "version": 2,
+  "buildCommand": "CI=false npm run build",
   "outputDirectory": "build",
-  "installCommand": "npm install",
-  "devCommand": "npm start",
-  "env": {
-    "CI": "false"
-  },
-  "build": {
-    "env": {
-      "CI": "false"
-    }
-  },
+  "framework": "create-react-app",
   "rewrites": [
     {
       "source": "/(.*)",
       "destination": "/index.html"
     }
+  ],
+  "headers": [
+    {
+      "source": "/static/(.*)",
+      "headers": [
+        {
+          "key": "Cache-Control",
+          "value": "public, max-age=31536000, immutable"
+        }
+      ]
+    }
   ]
 }