**Add artwork URL to queue metadata**

Enhanced queue metadata by including the track's artwork URL in the serialized output. This allows clients to display album art or related visuals alongside track information.

src/main/java/me/bobert/netneutrality/music/QueueManager.java

@@ -75,6 +75,7 @@ public class QueueManager {
         item.put("identifier", info.getTrack().getInfo().getIdentifier());
         item.put("title", info.getTrack().getInfo().getTitle());
         item.put("uri", info.getTrack().getInfo().getUri());
+        item.put("artworkUrl", info.getTrack().getInfo().getArtworkUrl());
         item.put("requesterId", info.getRequester() == null ? null : info.getRequester().getId());
         return item;
     }