refactor: tighten shadcn admin ui polish

frontend/src/components/app/AppTopbar.tsx

@@ -19,14 +19,14 @@ export function AppTopbar() {
         <Badge variant="info">本地环境</Badge>
         <Separator orientation="vertical" className="h-5" />
         <Button variant="ghost" size="icon" aria-label="通知">
-          <Bell className="size-4" />
+          <Bell data-icon="inline-start" />
         </Button>
         <Button variant="ghost" className="gap-2">
-          <UserRound className="size-4" />
+          <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 className="size-4" />
+          <LogOut data-icon="inline-start" />
           <span>退出</span>
         </Button>
       </div>