feat(l10n): add extension for localized banner ad shape names

- Create new extension on BannerAdShape to provide localized string representations
- Add l10n method to return localized name based on context and shape type
- Implement switch case for different banner ad shapes (square and rectangle)

Author: fulleni

lib/shared/extensions/banner_ad_shape_l10n.dart

@@ -0,0 +1,19 @@
+import 'package:core/core.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_news_app_web_dashboard_full_source_code/l10n/l10n.dart';
+
+/// {@template banner_ad_shape_l10n}
+/// Extension on [BannerAdShape] to provide localized string representations.
+/// {@endtemplate}
+extension BannerAdShapeL10n on BannerAdShape {
+  /// Returns the localized name for a [BannerAdShape].
+  String l10n(BuildContext context) {
+    final l10n = context.l10n;
+    switch (this) {
+      case BannerAdShape.square:
+        return l10n.bannerAdShapeSquare;
+      case BannerAdShape.rectangle:
+        return l10n.bannerAdShapeRectangle;
+    }
+  }
+}