refactor: standardize admin page shell

frontend/src/features/system/SystemUsersPage.tsx

@@ -4,6 +4,7 @@ import { AppField } from '@/components/app/AppField'
 import { AppDataTable, type AppDataTableColumn } from '@/components/app/AppDataTable'
 import { AppEmptyState } from '@/components/app/AppEmptyState'
 import { AppFilterBar } from '@/components/app/AppFilterBar'
+import { AppPage } from '@/components/app/AppPage'
 import { AppPageHeader } from '@/components/app/AppPageHeader'
 import { Badge } from '@/components/ui/badge'
 import { Button } from '@/components/ui/button'
@@ -138,8 +139,7 @@ export function SystemUsersPage() {
   ]
 
   return (
-    <main className="min-h-screen bg-background p-6 text-foreground">
-      <div className="mx-auto flex max-w-7xl flex-col gap-4">
+    <AppPage>
         <AppPageHeader title="用户管理" />
 
         <form className="grid gap-3 rounded-lg border border-border bg-surface p-3 md:grid-cols-[1fr_1fr_1fr_1fr_auto] md:items-end" onSubmit={handleCreateUser}>
@@ -180,8 +180,7 @@ export function SystemUsersPage() {
           onClose={() => setEditingUser(null)}
           onSaved={load}
         />
-      </div>
-    </main>
+    </AppPage>
   )
 }