Fix iOS zoom and production API configuration

- Fix iOS auto-zoom on input focus (set font-size: 16px)
- Lock viewport to prevent manual zoom (maximum-scale=1.0)
- Make API URL configurable via VITE_API_URL environment variable
- Add TypeScript types for Vite environment variables
- Create deployment guide with Vercel/backend setup instructions
- Add .env.example for local development configuration
- Add vercel.json for unified frontend/backend deployment

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

vercel.json

@@ -0,0 +1,27 @@
+{
+  "version": 2,
+  "builds": [
+    {
+      "src": "dist/index.html",
+      "use": "@vercel/static"
+    },
+    {
+      "src": "server/src/server.ts",
+      "use": "@vercel/node"
+    }
+  ],
+  "routes": [
+    {
+      "src": "/api/(.*)",
+      "dest": "server/src/server.ts"
+    },
+    {
+      "src": "/health",
+      "dest": "server/src/server.ts"
+    },
+    {
+      "src": "/(.*)",
+      "dest": "/dist/$1"
+    }
+  ]
+}