feat: migrate runtime backend to node server

server-node/build.mjs

@@ -0,0 +1,13 @@
+import esbuild from 'esbuild';
+
+await esbuild.build({
+  entryPoints: ['src/server.ts'],
+  bundle: true,
+  platform: 'node',
+  format: 'esm',
+  target: 'node22',
+  outfile: 'dist/server.js',
+  sourcemap: true,
+  packages: 'external',
+  tsconfig: 'tsconfig.json',
+});