feat(admin): 完善站点设置、内容回收站与后台菜单分组

新增站点设置与内容管理（含已删除恢复/清除），用户页改用独有运营指标，并按概览/内容/成员与经济/站点重组侧栏。

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

frontend/app/admin/settings/page.tsx

@@ -0,0 +1,21 @@
+import type { Metadata } from "next";
+import { cookies } from "next/headers";
+import { getMeCached, getPublicSettingsCached } from "@/lib/serverData";
+import { authCookieHeader } from "@/lib/cookies";
+import { isSuperOrOwner } from "@/lib/roles";
+import Forbidden from "../Forbidden";
+import SettingsAdmin from "./SettingsAdmin";
+
+export const metadata: Metadata = {
+  title: "站点设置",
+};
+
+export default async function AdminSettingsPage() {
+  const cookie = authCookieHeader(await cookies());
+  const me = await getMeCached(cookie || undefined);
+  if (!me.user || !isSuperOrOwner(me.user.role)) {
+    return <Forbidden text="站点设置仅超级管理员和站长可操作。" />;
+  }
+  const settings = await getPublicSettingsCached();
+  return <SettingsAdmin initial={settings} />;
+}