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/shell/tablet_shell.dart

@@ -10,6 +10,7 @@ import '../screens/account_page.dart';
 import '../screens/connect_page.dart';
 import '../screens/contact_page.dart';
 import '../screens/nodes_page.dart';
+import '../screens/notifications_page.dart';
 import '../screens/settings_page.dart';
 import '../screens/stats_page.dart';
 import '../state/app_providers.dart';
@@ -27,7 +28,7 @@ class TabletShell extends ConsumerWidget {
     final t = ref.watch(appTextProvider);
     final view = ref.watch(navViewProvider);
 
-    // 「我的」移到侧栏顶部品牌按钮(见 NavSidebar);设置/联系我们对齐桌面侧栏。
+    // 「我的」经侧栏底部 PlanBadgeCard 进入(见 NavSidebar;品牌块本身不可点);设置/联系我们对齐桌面侧栏。
     final items = <NavSidebarItem>[
       (icon: PangolinIcons.power, label: t.tabConnect, view: NavView.connect),
       (icon: PangolinIcons.globe, label: t.tabServers, view: NavView.servers),
@@ -61,11 +62,19 @@ class TabletShell extends ConsumerWidget {
           return const SettingsPage();
         case NavView.contact:
           return const ContactPage();
+        case NavView.notifications:
+          return NotificationsScreen(t: t, embedded: true);
         default: // account / plans / redeem / devices → 账户（其余下钻在账户页内）
           return const AccountPage(isWide: true);
       }
     }
 
+    // 通知子页返回目标:回账户(镜像桌面 desktop_shell.dart::backTarget)。
+    VoidCallback? backTarget() {
+      if (view == NavView.notifications) return () => go(NavView.account);
+      return null;
+    }
+
     return ColoredBox(
       color: c.bg,
       // iPad 上内容会顶到状态栏(时间/电量/notch)。SafeArea 加顶部安全区,避开重叠;
@@ -76,7 +85,13 @@ class TabletShell extends ConsumerWidget {
           NavSidebar(items: items, width: 232, dense: false),
           Expanded(
             child: Column(children: [
-              ContentTopBar(title: titles[view] ?? t.tabMe, showThemeToggle: false, titleSize: 19),
+              ContentTopBar(
+                title: titles[view] ?? t.tabMe,
+                onBack: backTarget(),
+                onBell: () => go(NavView.notifications),
+                showThemeToggle: false,
+                titleSize: 19,
+              ),
               Expanded(child: content()),
             ]),
           ),