style: elevate enterprise admin visual foundation

frontend/src/components/app/AppTopbar.tsx

@@ -13,7 +13,7 @@ export function AppTopbar({ onMobileMenuClick }: AppTopbarProps) {
   const { logout, user } = useAuth()
 
   return (
-    <header className="sticky top-0 z-20 flex h-14 items-center justify-between border-b border-border bg-surface/95 px-6 backdrop-blur">
+    <header className="sticky top-0 z-20 flex h-14 items-center justify-between border-b border-border/80 bg-surface/95 px-4 shadow-sm backdrop-blur sm:px-6 lg:px-8">
       <div className="flex min-w-0 items-center gap-2 text-sm">
         <Button
           variant="ghost"
@@ -24,23 +24,23 @@ export function AppTopbar({ onMobileMenuClick }: AppTopbarProps) {
         >
           <Menu data-icon="inline-start" />
         </Button>
-        <span className="font-medium text-foreground">AI 工单平台</span>
-        <ChevronRight className="size-4 text-muted-foreground" />
+        <span className="hidden font-medium text-foreground sm:inline">企业服务治理中台</span>
+        <ChevronRight className="hidden size-4 text-muted-foreground sm:block" />
         <span className="truncate text-muted-foreground">当前工作区</span>
       </div>
       <div className="flex items-center gap-3">
-        <Badge variant="info">本地环境</Badge>
+        <Badge variant="outline" className="hidden sm:inline-flex">本地环境</Badge>
         <Separator orientation="vertical" className="h-5" />
         <Button variant="ghost" size="icon" aria-label="通知">
           <Bell data-icon="inline-start" />
         </Button>
-        <Button variant="ghost" className="gap-2">
+        <Button variant="ghost" className="hidden gap-2 sm:inline-flex">
           <UserRound data-icon="inline-start" />
           <span>{user?.display_name || user?.username || '当前用户'}</span>
         </Button>
         <Button variant="outline" className="gap-2" onClick={() => void logout()}>
           <LogOut data-icon="inline-start" />
-          <span>退出</span>
+          <span className="hidden sm:inline">退出</span>
         </Button>
       </div>
     </header>