feat(ads): implement AdService for ad management

- Create AdService class to handle ad operations
- Add initialize() method for ad provider setup
- Implement getAd() method to retrieve and wrap ads in AdFeedItem
- Include error handling and logging for ad requests

Author: fulleni

lib/ads/ad_service.dart

@@ -0,0 +1,59 @@
+import 'package:flutter_news_app_mobile_client_full_source_code/ads/ad_provider.dart';
+import 'package:flutter_news_app_mobile_client_full_source_code/ads/models/ad_feed_item.dart';
+import 'package:logging/logging.dart';
+import 'package:uuid/uuid.dart';
+
+/// {@template ad_service}
+/// A service responsible for managing and providing ads to the application.
+///
+/// This service acts as an intermediary between the application's UI/logic
+/// and the underlying ad network providers (e.g., AdMob). It handles
+/// requesting ads and wrapping them in a generic [AdFeedItem] for use
+/// in the feed.
+/// {@endtemplate}
+class AdService {
+  /// {@macro ad_service}
+  ///
+  /// Requires an [AdProvider] to be injected, which will be used to
+  /// load ads from a specific ad network.
+  AdService({required AdProvider adProvider, Logger? logger})
+      : _adProvider = adProvider,
+        _logger = logger ?? Logger('AdService');
+
+  final AdProvider _adProvider;
+  final Logger _logger;
+  final Uuid _uuid = const Uuid();
+
+  /// Initializes the underlying ad provider.
+  ///
+  /// This should be called once at application startup.
+  Future<void> initialize() async {
+    _logger.info('Initializing AdService...');
+    await _adProvider.initialize();
+    _logger.info('AdService initialized.');
+  }
+
+  /// Retrieves a loaded native ad wrapped as an [AdFeedItem].
+  ///
+  /// This method delegates the ad loading to the injected [AdProvider].
+  /// If an ad is successfully loaded, it's wrapped in an [AdFeedItem]
+  /// with a unique ID.
+  ///
+  /// Returns an [AdFeedItem] if an ad is available, otherwise `null`.
+  Future<AdFeedItem?> getAd() async {
+    _logger.info('Requesting native ad from AdProvider...');
+    try {
+      final nativeAd = await _adProvider.loadNativeAd();
+      if (nativeAd != null) {
+        _logger.info('Native ad successfully loaded and wrapped.');
+        return AdFeedItem(id: _uuid.v4(), nativeAd: nativeAd);
+      } else {
+        _logger.info('No native ad loaded by AdProvider.');
+        return null;
+      }
+    } catch (e) {
+      _logger.severe('Error getting ad from AdProvider: $e');
+      return null;
+    }
+  }
+}