imporved app bar; added quick actions;

app/lib/features/search_browser/domain/entities/sheet.dart

@@ -1,6 +1,8 @@
 import 'package:bang_navigator/features/search_browser/domain/entities/modes.dart';
+import 'package:fast_equatable/fast_equatable.dart';
 
-sealed class Sheet {}
+// ignore: missing_override_of_must_be_overridden
+sealed class Sheet with FastEquatable {}
 
 class CreateTab extends Sheet {
   final String? content;
@@ -9,6 +11,18 @@ class CreateTab extends Sheet {
   bool get hasParameters => content != null || preferredTool != null;
 
   CreateTab({this.content, this.preferredTool});
+
+  @override
+  bool get cacheHash => true;
+
+  @override
+  List<Object?> get hashParameters => [content, preferredTool];
 }
 
-class ViewTabs extends Sheet {}
+class ViewTabs extends Sheet {
+  @override
+  bool get cacheHash => true;
+
+  @override
+  List<Object?> get hashParameters => [];
+}