added simple search feature

lib/widgets/search_widgets/search_bar_widget.dart

@@ -0,0 +1,16 @@
+import 'package:flutter/material.dart';
+
+class SearchBarWidget extends StatelessWidget {
+  const SearchBarWidget({super.key, required this.onEditingComplete});
+
+  final Function(String searchString) onEditingComplete;
+
+  @override
+  Widget build(BuildContext context) {
+    TextEditingController searchBarController = TextEditingController();
+    return TextField(
+      controller: searchBarController,
+      onEditingComplete: () => onEditingComplete(searchBarController.text),
+    );
+  }
+}

lib/widgets/search_widgets/search_results_widget.dart

@@ -0,0 +1,36 @@
+import 'package:flutter/material.dart';
+
+import '../../model/bookmark.dart';
+import '../../service/notifying.dart';
+import '../../service/url_launcher.dart';
+
+class SearchResultsWidget extends StatelessWidget {
+  const SearchResultsWidget({super.key, required this.bookmarks});
+
+  final Iterable<Bookmark> bookmarks;
+
+  Widget bookmarkListItemBuilder(BuildContext context, int index) {
+    final bookmark = bookmarks.elementAt(index);
+    return ListTile(
+      title: Text(bookmark.name),
+      onTap: () => launchUrlFromString(bookmark.link).then((errorCode) {
+        if (context.mounted && errorCode != UrlLaunchErrorCode.none) {
+          Notifying.showUrlErrorSnackbar(context, errorCode);
+        } else if (context.mounted) {
+          Navigator.of(context).pop();
+        }
+      }),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (bookmarks.isNotEmpty) {
+      return ListView.builder(
+        itemBuilder: bookmarkListItemBuilder,
+        itemCount: bookmarks.length,
+      );
+    }
+    return Center(child: Text('Start searching'));
+  }
+}