refactor(ui): [UI8] 彻底移除遗留Card并补充下拉框中文化

client/src/pages/FeatureFlagsPage.tsx

@@ -138,7 +138,7 @@ export function FeatureFlagsPage() {
         <p className="rounded-lg border border-red-200 bg-red-50 px-3 py-2 text-sm text-red-600">{error}</p>
       ) : null}
 
-      <div className="card-std space-y-4">
+      <div className="card-std p-6 space-y-4">
         <h3 className="text-base font-semibold text-zinc-900">开关列表</h3>
 
         {flagsQuery.isLoading ? <TableSkeleton columns={6} rows={2} /> : null}