feat(headlines-search): add TopicItemWidget for search results

- Create TopicItemWidget to display Topic search results
- Replace temporary ListTile with TopicItemWidget in search results
- Add navigation to Topic details page on item tap

Author: fulleni

lib/headlines-search/view/headlines_search_page.dart

@@ -9,6 +9,7 @@ import 'package:ht_main/app/bloc/app_bloc.dart';
 import 'package:ht_main/headlines-search/bloc/headlines_search_bloc.dart';
 // import 'package:ht_main/headlines-search/widgets/country_item_widget.dart';
 import 'package:ht_main/headlines-search/widgets/source_item_widget.dart';
+import 'package:ht_main/headlines-search/widgets/topic_item_widget.dart';
 import 'package:ht_main/l10n/l10n.dart';
 import 'package:ht_main/router/routes.dart';
 import 'package:ht_main/shared/extensions/content_type_extensions.dart';
@@ -332,8 +333,7 @@ class _HeadlinesSearchViewState extends State<_HeadlinesSearchView> {
                           }
                           return tile;
                         } else if (feedItem is Topic) {
-                          // TODO(user): Create a TopicItemWidget similar to CategoryItemWidget
-                          return ListTile(title: Text(feedItem.name));
+                          return TopicItemWidget(topic: feedItem);
                         } else if (feedItem is Source) {
                           return SourceItemWidget(source: feedItem);
                         } else if (feedItem is Ad) {

lib/headlines-search/widgets/topic_item_widget.dart

@@ -0,0 +1,32 @@
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:ht_main/entity_details/view/entity_details_page.dart';
+import 'package:ht_main/router/routes.dart';
+import 'package:ht_shared/ht_shared.dart';
+
+/// A simple widget to display a Topic search result.
+class TopicItemWidget extends StatelessWidget {
+  const TopicItemWidget({required this.topic, super.key});
+
+  final Topic topic;
+
+  @override
+  Widget build(BuildContext context) {
+    return ListTile(
+      title: Text(topic.name),
+      subtitle: topic.description.isNotEmpty
+          ? Text(
+              topic.description,
+              maxLines: 2,
+              overflow: TextOverflow.ellipsis,
+            )
+          : null,
+      onTap: () {
+        context.push(
+          Routes.topicDetails,
+          extra: EntityDetailsPageArguments(entity: topic),
+        );
+      },
+    );
+  }
+}