refactor(client): SubScaffold 六合一(视觉零变化)+ tablet 注释订正 + 平板通知铃入口(#20)

client/lib/screens/notifications_page.dart

@@ -7,9 +7,9 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../l10n/app_text.dart';
 import '../pangolin_theme.dart';
-import '../widgets/page_body.dart';
 import '../widgets/pangolin_icons.dart';
 import '../widgets/status_pill.dart';
+import '../widgets/sub_scaffold.dart';
 
 typedef _Notice = ({
   IconData icon,
@@ -137,24 +137,12 @@ class NotificationsScreen extends ConsumerWidget {
           ],
         );
 
-    if (embedded) return PageBody(child: content());
-    return Scaffold(
-      backgroundColor: c.bg,
-      body: SafeArea(
-        child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
-          Padding(
-            padding: const EdgeInsets.fromLTRB(8, 6, 16, 10),
-            child: Row(children: [
-              IconButton(
-                onPressed: onBack ?? () => Navigator.of(context).maybePop(),
-                icon: Icon(PangolinIcons.arrowLeft, size: 22, color: c.fg1),
-              ),
-              Text(t.notifTitle, style: PangolinText.h3.copyWith(color: c.fg1, fontWeight: FontWeight.w700)),
-            ]),
-          ),
-          Expanded(child: PageBody(child: content())),
-        ]),
-      ),
+    return SubScaffold(
+      title: t.notifTitle,
+      onBack: onBack,
+      embedded: embedded,
+      wrapPageBody: true,
+      child: content(),
     );
   }
 }