feat: Fix loop uses sinceState instead of newSinceState, causing infinite loops.

lib/features/labels/presentation/extensions/handle_label_websocket_extension.dart

@@ -36,8 +36,10 @@ extension HandleLabelWebsocketExtension on LabelController {
 
       if (refreshState is GetLabelChangesSuccess) {
         await _handleGetLabelChangesSuccess(refreshState);
-      } else {
+      } else if (refreshState != null) {
         onDataFailureViewState(refreshState);
+      } else {
+        logWarning('HandleLabelWebsocketExtension::handleWebSocketMessage: refreshState is null');
       }
     } catch (e, stackTrace) {
       logWarning(

lib/features/labels/presentation/utils/label_utils.dart

@@ -244,6 +244,10 @@ class LabelUtils {
     }
   }
 
+  /// Applies label changes to [currentLabels] **in place**.
+  ///
+  /// Removes labels matching [destroyedIds], [created], and [updated] IDs,
+  /// then appends [created] and [updated] labels.
   static void applyLabelChanges({
     required List<Label> currentLabels,
     required List<Label> created,