refactor(headlines-search): update RemoteConfigService parameter name

- Change 'appConfig' to 'remoteConfig' in _feedInjectorService.injectItems calls
- This change improves code readability and consistency with parameter naming

Author: fulleni

lib/headlines-search/bloc/headlines_search_bloc.dart

@@ -109,7 +109,7 @@ class HeadlinesSearchBloc
               final injectedItems = _feedInjectorService.injectItems(
                 headlines: headlines,
                 user: currentUser,
-                appConfig: appConfig,
+                remoteConfig: appConfig,
                 currentFeedItemCount: successState.items.length,
               );
               emit(
@@ -219,7 +219,7 @@ class HeadlinesSearchBloc
           processedItems = _feedInjectorService.injectItems(
             headlines: headlines,
             user: currentUser,
-            appConfig: appConfig,
+            remoteConfig: appConfig,
             currentFeedItemCount: 0,
           );
         case ContentType.topic: