feat(content_management): add archived sources bloc

- Create ArchivedSourcesBloc class
- Define ArchivedSourcesEvent sealed class
- Define ArchivedSourcesState sealed class
- Add ArchivedSourcesInitial state

Author: fulleni

lib/content_management/bloc/archived_sources/archived_sources_bloc.dart

@@ -0,0 +1,13 @@
+import 'package:bloc/bloc.dart';
+import 'package:equatable/equatable.dart';
+
+part 'archived_sources_event.dart';
+part 'archived_sources_state.dart';
+
+class ArchivedSourcesBloc extends Bloc<ArchivedSourcesEvent, ArchivedSourcesState> {
+  ArchivedSourcesBloc() : super(ArchivedSourcesInitial()) {
+    on<ArchivedSourcesEvent>((event, emit) {
+      // TODO: implement event handler
+    });
+  }
+}

lib/content_management/bloc/archived_sources/archived_sources_event.dart

@@ -0,0 +1,8 @@
+part of 'archived_sources_bloc.dart';
+
+sealed class ArchivedSourcesEvent extends Equatable {
+  const ArchivedSourcesEvent();
+
+  @override
+  List<Object> get props => [];
+}

lib/content_management/bloc/archived_sources/archived_sources_state.dart

@@ -0,0 +1,10 @@
+part of 'archived_sources_bloc.dart';
+
+sealed class ArchivedSourcesState extends Equatable {
+  const ArchivedSourcesState();
+  
+  @override
+  List<Object> get props => [];
+}
+
+final class ArchivedSourcesInitial extends ArchivedSourcesState {}