Configure Next.js standalone output for deployment

next.config.ts

@@ -14,7 +14,7 @@ const nextConfig: NextConfig = {
   turbopack: {
     root: path.resolve(__dirname),
   },
-  // output: "export" removed to allow server actions
+  output: "standalone",
   // Required by the How It Works 3D experience. React StrictMode double-invokes
   // mount/effects in dev, which tears down and re-creates the WebGL context of
   // the heavy 32MB scene mid-initialization — the context is lost ("THREE.