feat(shell): 桌面侧栏加 Account 一级项 + 顶栏通知铃铛 + invite/notifications 视图接线

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

client/lib/shell/desktop_shell.dart

@@ -36,6 +36,7 @@ class DesktopShell extends ConsumerWidget {
       (icon: PangolinIcons.power, label: t.tabConnect, view: NavView.connect),
       (icon: PangolinIcons.globe, label: t.tabServers, view: NavView.servers),
       (icon: PangolinIcons.chartNoAxesColumn, label: t.tabStats, view: NavView.stats),
+      (icon: PangolinIcons.user, label: t.tabMe, view: NavView.account),
       (icon: PangolinIcons.settings, label: t.settingsTitle, view: NavView.settings),
       (icon: PangolinIcons.messageCircle, label: t.contactTitle, view: NavView.contact),
     ];
@@ -54,6 +55,7 @@ class DesktopShell extends ConsumerWidget {
       NavView.payment: t.paymentTitle,
       NavView.orders: t.ordersTitle,
       NavView.invite: t.inviteTitle,
+      NavView.notifications: t.notifTitle,
     };
 
     void go(NavView v) => ref.read(navViewProvider.notifier).state = v;
@@ -98,6 +100,7 @@ class DesktopShell extends ConsumerWidget {
     // 其余下钻子页（含 purchase 本身）→ account。
     VoidCallback? backTarget() {
       if (view == NavView.payment) return () => go(NavView.purchase);
+      if (view == NavView.notifications) return () => go(NavView.account);
       if (kAccountSubViews.contains(view)) return () => go(NavView.account);
       return null;
     }
@@ -111,6 +114,7 @@ class DesktopShell extends ConsumerWidget {
             ContentTopBar(
               title: titles[view] ?? t.brand,
               onBack: backTarget(),
+              onBell: () => go(NavView.notifications),
             ),
             Expanded(child: content()),
           ]),