refactor(headlines-feed): add missing annotation for pagination comment

- Add '//' to continue the comment about pagination
- Improve code readability by clearly marking the section related to pagination

Author: fulleni

lib/headlines-feed/bloc/headlines_feed_bloc.dart

@@ -111,6 +111,7 @@ class HeadlinesFeedBloc extends Bloc<HeadlinesFeedEvent, HeadlinesFeedState> {
       );
 
       // For pagination, only inject ad placeholders, not feed actions.
+      // 
       // This method injects stateless `AdPlaceholder` markers into the feed.
       // The full ad loading and lifecycle is managed by the UI layer.
       // See `FeedDecoratorService` for a detailed explanation.

lib/shared/services/feed_decorator_service.dart

@@ -2,7 +2,6 @@ import 'dart:math';
 
 import 'package:core/core.dart';
 import 'package:data_repository/data_repository.dart';
-import 'package:flutter_news_app_mobile_client_full_source_code/ads/ad_service.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/ads/models/ad_placeholder.dart'; // Import the new AdPlaceholder model
 import 'package:flutter_news_app_mobile_client_full_source_code/ads/models/ad_theme_style.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/router/routes.dart';