完善站点运营设置：分路由管理、登录可见评论、邮件模板内联与关闭注册 SSR。

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

frontend/app/admin/settings/mail/page.tsx

@@ -0,0 +1,10 @@
+import type { Metadata } from "next";
+import ModuleSettings from "../ModuleSettings";
+
+export const metadata: Metadata = {
+  title: "邮件服务",
+};
+
+export default function MailSettingsPage() {
+  return <ModuleSettings name="mail" />;
+}