refactor(headlines-feed): remove decorator dismissal functionality

- Remove FeedDecoratorDismissed event from headlines_feed_event.dart
- Remove _onFeedDecoratorDismissed handler from headlines_feed_bloc.dart
- Remove onDismiss callbacks from headlines_feed_page.dart
- Update imports and dependencies related to decorator dismissal

Author: fulleni

lib/headlines-feed/bloc/headlines_feed_bloc.dart

@@ -119,10 +119,6 @@ class HeadlinesFeedBloc extends Bloc<HeadlinesFeedEvent, HeadlinesFeedState> {
       _onHeadlinesFeedFiltersCleared,
       transformer: restartable(),
     );
-    on<FeedDecoratorDismissed>(
-      _onFeedDecoratorDismissed,
-      transformer: sequential(),
-    );
     on<CallToActionTapped>(_onCallToActionTapped, transformer: sequential());
     on<NavigationHandled>(_onNavigationHandled, transformer: sequential());
     on<_AppContentPreferencesChanged>(_onAppContentPreferencesChanged);
@@ -717,73 +713,6 @@ class HeadlinesFeedBloc extends Bloc<HeadlinesFeedEvent, HeadlinesFeedState> {
     }
   }
 
-  Future<void> _onFeedDecoratorDismissed(
-    FeedDecoratorDismissed event,
-    Emitter<HeadlinesFeedState> emit,
-  ) async {
-    _logger.info(
-      'Dismissing decorator: ${event.feedDecoratorType}. '
-      'Updating cache and UI.',
-    );
-    final currentUser = _appBloc.state.user;
-    if (currentUser == null) return;
-
-    // First, notify the AppBloc that the user has completed this action.
-    // This prevents the decorator from being shown again in future sessions.
-    _appBloc.add(
-      AppUserFeedDecoratorShown(
-        userId: currentUser.id,
-        feedDecoratorType: event.feedDecoratorType,
-        isCompleted: true,
-      ),
-    );
-
-    // Second, update the in-memory cache for the current session.
-    // This ensures the decorator is removed immediately from the current view
-    // and does not reappear when switching between feed filters.
-    final filterKey = _generateFilterKey(state.activeFilterId!, state.filter);
-    final cachedFeed = _feedCacheService.getFeed(filterKey);
-
-    if (cachedFeed == null) {
-      _logger.warning(
-        'Cannot update cache on decorator dismissal: '
-        'No cached feed found for key "$filterKey".',
-      );
-      // Fallback to just removing from the UI state if cache is not found.
-      final newFeedItems = List<FeedItem>.from(state.feedItems)
-        ..removeWhere((item) {
-          if (item is CallToActionItem) {
-            return item.decoratorType == event.feedDecoratorType;
-          }
-          if (item is ContentCollectionItem) {
-            return item.decoratorType == event.feedDecoratorType;
-          }
-          return false;
-        });
-      emit(state.copyWith(feedItems: newFeedItems));
-      return;
-    }
-
-    // Perform the "read-modify-write" cycle on the cache.
-    final newFeedItems = List<FeedItem>.from(cachedFeed.feedItems)
-      ..removeWhere((item) {
-        if (item is CallToActionItem) {
-          return item.decoratorType == event.feedDecoratorType;
-        } else if (item is ContentCollectionItem) {
-          return item.decoratorType == event.feedDecoratorType;
-        }
-        return false;
-      });
-
-    final updatedCachedFeed = cachedFeed.copyWith(feedItems: newFeedItems);
-    _feedCacheService.setFeed(filterKey, updatedCachedFeed);
-    _logger.info(
-      'Cache for key "$filterKey" updated after decorator dismissal.',
-    );
-
-    emit(state.copyWith(feedItems: newFeedItems));
-  }
-
   Future<void> _onCallToActionTapped(
     CallToActionTapped event,
     Emitter<HeadlinesFeedState> emit,

lib/headlines-feed/bloc/headlines_feed_event.dart

@@ -116,20 +116,6 @@ final class HeadlinesFeedFiltersCleared extends HeadlinesFeedEvent {
   List<Object> get props => [adThemeStyle];
 }
 
-/// {@template feed_decorator_dismissed}
-/// Event triggered when a user dismisses a feed decorator.
-/// {@endtemplate}
-final class FeedDecoratorDismissed extends HeadlinesFeedEvent {
-  /// {@macro feed_decorator_dismissed}
-  const FeedDecoratorDismissed({required this.feedDecoratorType});
-
-  /// The type of the decorator that was dismissed.
-  final FeedDecoratorType feedDecoratorType;
-
-  @override
-  List<Object> get props => [feedDecoratorType];
-}
-
 /// {@template call_to_action_tapped}
 /// Event triggered when a user taps the call-to-action button on a decorator.
 /// {@endtemplate}

lib/headlines-feed/view/headlines_feed_page.dart

@@ -322,13 +322,6 @@ class _HeadlinesFeedPageState extends State<HeadlinesFeedPage>
                                       CallToActionTapped(url: url),
                                     );
                               },
-                              onDismiss: (decoratorType) {
-                                context.read<HeadlinesFeedBloc>().add(
-                                      FeedDecoratorDismissed(
-                                        feedDecoratorType: decoratorType,
-                                      ),
-                                    );
-                              },
                             );
                           } else if (item is ContentCollectionItem) {
                             // Access AppBloc to get the user's content preferences,
@@ -400,13 +393,6 @@ class _HeadlinesFeedPageState extends State<HeadlinesFeedPage>
                                       ),
                                     );
                               },
-                              onDismiss: (decoratorType) {
-                                context.read<HeadlinesFeedBloc>().add(
-                                      FeedDecoratorDismissed(
-                                        feedDecoratorType: decoratorType,
-                                      ),
-                                    );
-                              },
                             );
                           }
                           return const SizedBox.shrink();