fix(headlines-search): enhance country search with pagination and filtering

- Add 'usage' filter to only include countries with active headlines
- Implement pagination to limit search results to a maximum number
- Update search logic to use the new filter and pagination options

Author: fulleni

lib/headlines-search/bloc/headlines_search_bloc.dart

@@ -175,7 +175,8 @@ class HeadlinesSearchBloc
               );
             case ContentType.country:
               response = await _countryRepository.readAll(
-                filter: {'q': searchTerm},
+                filter: {'q': searchTerm, 'usage': 'hasActiveHeadlines'},
+                pagination: const PaginationOptions(limit: _limit),
                 sort: [const SortOption('name', SortOrder.asc)],
               );
               emit(
@@ -260,7 +261,8 @@ class HeadlinesSearchBloc
           processedItems = rawResponse.items.cast<FeedItem>();
         case ContentType.country:
           rawResponse = await _countryRepository.readAll(
-            filter: {'q': searchTerm},
+            filter: {'q': searchTerm, 'usage': 'hasActiveHeadlines'},
+            pagination: const PaginationOptions(limit: _limit),
             sort: [const SortOption('name', SortOrder.asc)],
           );
           processedItems = rawResponse.items.cast<FeedItem>();