Refactor server startup to use environment variable for port configuration

src/server.ts

@@ -195,6 +195,7 @@ export function createServer(port: number): WebSocketServer {
 }
 
 if (isMain) {
-  createServer(3001);
-  console.log("DiscoveryServer listening on ws://localhost:3001");
+  const port = parseInt(process.env.PORT || "3001", 10);
+  createServer(port);
+  console.log(`DiscoveryServer listening on port ${port}`);
 }