feat: 可选社区上报与官方精选展柜

默认关闭，仪表盘一键开关；枢纽由运维配置收报，人工精选后展示于 /showcase。

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

frontend/src/pages/admin/AdminDashboardPage.tsx

@@ -7,6 +7,7 @@ import { api } from '../../api/client';
 import { useAdminGuard } from '../../layouts/AdminLayout';
 import type { AdminDashboard } from '../../api/types';
 import { cn } from '@/lib/utils';
+import CommunitySupportStrip from '../../components/admin/CommunitySupportStrip';
 
 export default function AdminDashboardPage() {
   const nav = useNavigate();
@@ -127,6 +128,8 @@ export default function AdminDashboardPage() {
         </div>
       </section>
 
+      <CommunitySupportStrip />
+
       <div className="admin-card">
         <div className="admin-card-head">
           <span>最新帖子</span>