use middleware for runtime backend proxy

web/next.config.mjs

@@ -2,14 +2,6 @@
 const nextConfig = {
   output: 'standalone',
   reactCompiler: true,
-  async rewrites() {
-    return [
-      {
-        source: "/api/:path*",
-        destination: `${process.env.BACKEND_URL || "http://localhost:8080"}/api/:path*`,
-      },
-    ];
-  },
 };
 
 export default nextConfig;