polish(admin): 抽出后台控件包并统一各页布局与交互

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/components/admin/AdminSwitch.tsx

@@ -0,0 +1,28 @@
+"use client";
+
+/** 后台唯一开关控件 */
+export default function AdminSwitch({
+  checked,
+  disabled,
+  onChange,
+  label,
+}: {
+  checked: boolean;
+  disabled?: boolean;
+  onChange: () => void;
+  label: string;
+}) {
+  return (
+    <button
+      type="button"
+      role="switch"
+      aria-checked={checked}
+      aria-label={label}
+      disabled={disabled}
+      onClick={onChange}
+      className="admin-switch"
+    >
+      <span className="admin-switch-knob" aria-hidden />
+    </button>
+  );
+}