feat: 添加 AI 服务状态监控和警告功能

- AI 配置页面添加服务健康状态显示（正常/降级/异常）
- 服务异常时显示红色警告卡片，展示错误信息和队列任务数
- 侧边栏 AI 配置入口添加红点警告徽章支持
- DesktopLayout 支持传递 aiServiceError 状态

AI 调用风险处理方案：
- 自动重试 3 次
- 失败后加入队列，后台定时重试
- 页面显示服务状态警告

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/components/layout/DesktopLayout.tsx

@@ -6,16 +6,18 @@ interface DesktopLayoutProps {
   children: React.ReactNode
   role?: 'creator' | 'agency' | 'brand'
   className?: string
+  aiServiceError?: boolean // AI 服务异常状态（仅品牌方使用）
 }
 
 export function DesktopLayout({
   children,
   role = 'creator',
   className = '',
+  aiServiceError = false,
 }: DesktopLayoutProps) {
   return (
     <div className={`h-screen bg-bg-page flex overflow-hidden ${className}`}>
-      <Sidebar role={role} />
+      <Sidebar role={role} aiServiceError={role === 'brand' ? aiServiceError : false} />
       <main className="flex-1 ml-[260px] p-8 overflow-y-auto overflow-x-hidden">
         <div className="min-h-full">
           {children}

frontend/components/navigation/Sidebar.tsx

@@ -25,6 +25,7 @@ interface NavItem {
   icon: React.ElementType
   label: string
   href: string
+  badge?: 'dot' | 'warning' | number // 支持红点、警告或数字徽章
 }
 
 // 达人端导航项
@@ -59,16 +60,27 @@ const brandNavItems: NavItem[] = [
 
 interface SidebarProps {
   role?: 'creator' | 'agency' | 'brand'
+  aiServiceError?: boolean // AI 服务是否异常
 }
 
-export function Sidebar({ role = 'creator' }: SidebarProps) {
+export function Sidebar({ role = 'creator', aiServiceError = false }: SidebarProps) {
   const pathname = usePathname() || ''
 
+  // 根据 aiServiceError 动态设置 AI 配置的徽章
+  const getBrandNavItems = (): NavItem[] => {
+    return brandNavItems.map(item => {
+      if (item.href === '/brand/ai-config' && aiServiceError) {
+        return { ...item, badge: 'warning' as const }
+      }
+      return item
+    })
+  }
+
   const navItems = role === 'creator'
     ? creatorNavItems
     : role === 'agency'
       ? agencyNavItems
-      : brandNavItems
+      : getBrandNavItems()
 
   const isActive = (href: string) => {
     if (href === `/${role}`) {
@@ -105,8 +117,24 @@ export function Sidebar({ role = 'creator' }: SidebarProps) {
                     : 'text-text-secondary hover:bg-bg-elevated/50'
                 )}
               >
-                <Icon className="w-5 h-5" />
-                <span className="text-[15px]">{item.label}</span>
+                <div className="relative">
+                  <Icon className="w-5 h-5" />
+                  {/* 警告徽章 */}
+                  {item.badge === 'warning' && (
+                    <span className="absolute -top-1 -right-1 w-2.5 h-2.5 bg-accent-coral rounded-full border-2 border-bg-card animate-pulse" />
+                  )}
+                  {/* 红点徽章 */}
+                  {item.badge === 'dot' && (
+                    <span className="absolute -top-0.5 -right-0.5 w-2 h-2 bg-accent-coral rounded-full" />
+                  )}
+                </div>
+                <span className="text-[15px] flex-1">{item.label}</span>
+                {/* 数字徽章 */}
+                {typeof item.badge === 'number' && item.badge > 0 && (
+                  <span className="px-1.5 py-0.5 text-xs bg-accent-coral text-white rounded-full min-w-[20px] text-center">
+                    {item.badge > 99 ? '99+' : item.badge}
+                  </span>
+                )}
               </Link>
             )
           })}