feat(account): filter active sources in AvailableSourcesBloc

- Add a filter to fetch only active sources from the repository
- Maintain existing sorting by name in ascending order
- Preserve pagination comment for future consideration

Author: fulleni

lib/account/bloc/available_sources_bloc.dart

@@ -33,7 +33,9 @@ class AvailableSourcesBloc
     emit(state.copyWith(status: AvailableSourcesStatus.loading));
     try {
       // TODO(fulleni): Add pagination if necessary for very large datasets.
+      // Filter to fetch only active sources.
       final response = await _sourcesRepository.readAll(
+        filter: {'status': ContentStatus.active.name},
         sort: [const SortOption('name', SortOrder.asc)],
       );
       emit(