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/widgets/content_top_bar.dart

@@ -9,15 +9,24 @@ import '../pangolin_theme.dart';
 import '../state/app_providers.dart';
 import '../state/connection_provider.dart';
 import '../state/nodes_provider.dart';
+import 'notification_bell.dart';
 import 'pangolin_icons.dart';
 
 class ContentTopBar extends ConsumerWidget {
-  const ContentTopBar({super.key, required this.title, this.onBack, this.showThemeToggle = true, this.titleSize = 17});
+  const ContentTopBar({
+    super.key,
+    required this.title,
+    this.onBack,
+    this.showThemeToggle = true,
+    this.titleSize = 17,
+    this.onBell,
+  });
 
   final String title;
   final VoidCallback? onBack;
   final bool showThemeToggle;
   final double titleSize;
+  final VoidCallback? onBell;
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
@@ -52,6 +61,10 @@ class ContentTopBar extends ConsumerWidget {
             color: conn.phase == VpnPhase.on ? c.success : c.fg3,
           ),
         ),
+        if (onBell != null) ...[
+          const SizedBox(width: 12),
+          NotificationBell(onTap: onBell, hasUnread: true),
+        ],
         if (showThemeToggle) ...[
           const SizedBox(width: 12),
           InkWell(

client/lib/widgets/notification_bell.dart

@@ -0,0 +1,42 @@
+// notification_bell.dart — 顶栏通知铃铛(带未读红点)
+//
+// 桌面顶栏(content_top_bar.dart)在主题切换旁挂一枚铃铛，点击进 NavView.notifications。
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../pangolin_theme.dart';
+import 'pangolin_icons.dart';
+
+class NotificationBell extends ConsumerWidget {
+  const NotificationBell({super.key, required this.onTap, this.hasUnread = false});
+
+  final VoidCallback? onTap;
+  final bool hasUnread;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final c = context.pangolin;
+
+    return InkWell(
+      onTap: onTap,
+      borderRadius: BorderRadius.circular(PangolinRadius.sm),
+      child: Padding(
+        padding: const EdgeInsets.all(6),
+        child: Stack(clipBehavior: Clip.none, children: [
+          Icon(PangolinIcons.bell, size: 18, color: c.fg2),
+          // TODO(spec-3): 未读态来自 notices provider，现暂由调用方写死演示。
+          if (hasUnread)
+            Positioned(
+              top: -1,
+              right: -1,
+              child: Container(
+                width: 7,
+                height: 7,
+                decoration: BoxDecoration(color: c.danger, shape: BoxShape.circle),
+              ),
+            ),
+        ]),
+      ),
+    );
+  }
+}