feat(entity_details): add events for bloc

- Add load requested event
- Add toggle follow event
- Add load more headlines event

Author: fulleni

lib/entity_details/bloc/entity_details_event.dart

@@ -0,0 +1,48 @@
+part of 'entity_details_bloc.dart';
+
+abstract class EntityDetailsEvent extends Equatable {
+  const EntityDetailsEvent();
+
+  @override
+  List<Object?> get props => [];
+}
+
+/// Event to load entity details and initial headlines.
+/// Can be triggered by passing an ID and type, or the full entity.
+class EntityDetailsLoadRequested extends EntityDetailsEvent {
+  const EntityDetailsLoadRequested({
+    this.entityId,
+    this.entityType,
+    this.entity,
+  }) : assert(
+            (entityId != null && entityType != null) || entity != null,
+            'Either entityId/entityType or entity must be provided.',
+          );
+
+  final String? entityId;
+  final EntityType? entityType;
+  final dynamic entity; // Category or Source
+
+  @override
+  List<Object?> get props => [entityId, entityType, entity];
+}
+
+/// Event to toggle the follow status of the current entity.
+class EntityDetailsToggleFollowRequested extends EntityDetailsEvent {
+  const EntityDetailsToggleFollowRequested();
+}
+
+/// Event to load more headlines for pagination.
+class EntityDetailsLoadMoreHeadlinesRequested extends EntityDetailsEvent {
+  const EntityDetailsLoadMoreHeadlinesRequested();
+}
+
+/// Internal event to notify the BLoC that user preferences have changed.
+class _EntityDetailsUserPreferencesChanged extends EntityDetailsEvent {
+  const _EntityDetailsUserPreferencesChanged(this.preferences);
+
+  final UserContentPreferences preferences;
+
+  @override
+  List<Object?> get props => [preferences];
+}