Fix Vercel routing: separate API and static file routes

vercel.json

@@ -8,8 +8,20 @@
   ],
   "routes": [
     {
-      "src": "/(.*)",
+      "src": "/api/(.*)",
       "dest": "/api/simple.js"
+    },
+    {
+      "src": "/health",
+      "dest": "/api/simple.js"
+    },
+    {
+      "src": "/(.*\\.(html|css|js|json|svg|png|jpg|jpeg|gif|ico|woff|woff2|ttf|eot))",
+      "dest": "/$1"
+    },
+    {
+      "src": "/(.*)",
+      "dest": "/index.html"
     }
   ],
   "env": {