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

lib/features/labels/data/network/label_api.dart

@@ -19,6 +19,8 @@ import 'package:uuid/uuid.dart';
 class LabelApi
     with HandleSetErrorMixin, SessionMixin, BatchGetLabelProcessingMixin {
 
+  static const int _defaultMaxChanges = 128;
+
   final HttpClient _httpClient;
   final Uuid _uuid;
 
@@ -179,7 +181,7 @@ class LabelApi
     final changesLabelMethod = ChangesLabelMethod(
       accountId,
       sinceState,
-      maxChanges: UnsignedInt(128),
+      maxChanges: UnsignedInt(_defaultMaxChanges),
     );
     final changesLabelInvocation =
         jmapRequestBuilder.invocation(changesLabelMethod);

lib/features/labels/data/repository/label_repository_impl.dart

@@ -50,7 +50,7 @@ class LabelRepositoryImpl extends LabelRepository {
       final changesResponse = await _labelDatasource.getLabelChanges(
         session,
         accountId,
-        sinceState,
+        newSinceState,
       );
 
       hasMoreChanges = changesResponse.hasMoreChanges;

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,