feat: add Railway deploy workflow and Bun server\n\n- Bun HTTP server listening on PORT\n- start script for Nixpacks\n- GitHub Action for Railway deploy

index.ts

@@ -1 +1,12 @@
-console.log("Hello via Bun!");
+const port = Number(process.env.PORT || 3000);
+
+const server = Bun.serve({
+  port,
+  fetch(_req) {
+    return new Response("Hello via Bun!", {
+      headers: { "content-type": "text/plain; charset=utf-8" },
+    });
+  },
+});
+
+console.log(`Server running on http://localhost:${server.port}`);