feat(shared): add in-article ad slot type localization extension

- Create new extension on InArticleAdSlotType for localized string representations
- Add l10n method to return localized name based on ad slot type
- Update extensions.dart to export the new localization extension

Author: fulleni

lib/shared/extensions/extensions.dart

@@ -1,5 +1,6 @@
 export 'app_user_role_l10n.dart';
 export 'content_status_l10n.dart';
 export 'feed_decorator_type_l10n.dart';
+export 'in_article_ad_slot_type_l10n.dart';
 export 'source_type_l10n.dart';
 export 'string_truncate.dart';

lib/shared/extensions/in_article_ad_slot_type_l10n.dart

@@ -0,0 +1,21 @@
+import 'package:core/core.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_news_app_web_dashboard_full_source_code/l10n/l10n.dart';
+
+/// {@template in_article_ad_slot_type_l10n}
+/// Extension on [InArticleAdSlotType] to provide localized string representations.
+/// {@endtemplate}
+extension InArticleAdSlotTypeL10n on InArticleAdSlotType {
+  /// Returns the localized name for an [InArticleAdSlotType].
+  String l10n(BuildContext context) {
+    final l10n = context.l10n;
+    switch (this) {
+      case InArticleAdSlotType.belowMainArticleImage:
+        return l10n.inArticleAdSlotTypeBelowMainArticleImage;
+      case InArticleAdSlotType.aboveArticleContinueReadingButton:
+        return l10n.inArticleAdSlotTypeAboveArticleContinueReadingButton;
+      case InArticleAdSlotType.belowArticleContinueReadingButton:
+        return l10n.inArticleAdSlotTypeBelowArticleContinueReadingButton;
+    }
+  }
+}