feat: no titlebar on macOS

Fixes #136

lib/view/page/server/detail.dart

@@ -14,6 +14,7 @@ import '../../../data/res/default.dart';
 import '../../../data/res/ui.dart';
 import '../../../data/store/setting.dart';
 import '../../../locator.dart';
+import '../../widget/custom_appbar.dart';
 import '../../widget/round_rect_card.dart';
 
 class ServerDetailPage extends StatefulWidget {
@@ -75,7 +76,7 @@ class _ServerDetailPageState extends State<ServerDetailPage>
 
   Widget _buildMainPage(Server si) {
     return Scaffold(
-      appBar: AppBar(
+      appBar: CustomAppBar(
         title: Text(si.spi.name, style: textSize18),
       ),
       body: ReorderableListView.builder(

lib/view/page/server/edit.dart

@@ -15,6 +15,7 @@ import '../../../data/provider/server.dart';
 import '../../../data/res/ui.dart';
 import '../../../data/store/private_key.dart';
 import '../../../locator.dart';
+import '../../widget/custom_appbar.dart';
 import '../../widget/tag/editor.dart';
 import '../private_key/edit.dart';
 
@@ -116,7 +117,7 @@ class _ServerEditPageState extends State<ServerEditPage> with AfterLayoutMixin {
       icon: const Icon(Icons.delete),
     );
     final actions = widget.spi != null ? [delBtn] : null;
-    return AppBar(
+    return CustomAppBar(
       title: Text(_s.edit, style: textSize18),
       actions: actions,
     );