Fix: getAddress() returns by value, use auto not auto&

Author: wu-vincent

include/listener.h

@@ -28,7 +28,7 @@ class ExampleListener {
         event.setJoinMessage(endstone::ColorFormat::Yellow + player.getName() + " joined the game");
 
         // Log the player's network address (useful for debugging, not shown to players)
-        auto &addr = player.getAddress();
+        auto addr = player.getAddress();
         plugin_.getLogger().info("{} joined from {}:{}", player.getName(), addr.getHostname(), addr.getPort());
     }