fix(admin): 后台列表切换保留当前内容，去掉加载占位

用户档案、用户列表、内容筛选与公告页等数据到达后再换视图，避免滚动条闪动。

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

frontend/lib/api.ts

@@ -1245,6 +1245,19 @@ export async function fetchAnnouncementDetail(
   return res.json();
 }
 
+// SSR 后台公告列表（含草稿）
+export async function fetchAdminAnnouncements(
+  cookieHeader?: string
+): Promise<{ announcements: Announcement[] }> {
+  const res = await fetch(
+    `${API_BASE}/api/admin/announcements`,
+    ssrInit(cookieHeaders(cookieHeader))
+  );
+  const data = await res.json().catch(() => ({}));
+  if (!res.ok) throw new Error(data.error || "获取公告列表失败");
+  return data as { announcements: Announcement[] };
+}
+
 // 后台：公告列表（含草稿）
 export async function apiAdminListAnnouncements(): Promise<{ announcements: Announcement[] }> {
   const res = await fetchWithRefresh("/api/admin/announcements", {
@@ -1524,6 +1537,20 @@ export async function fetchAdminUserAudit(
   return data as AdminUserAuditProfile;
 }
 
+export async function fetchAdminUserAuditPosts(
+  id: number,
+  page = 1,
+  cookieHeader?: string
+): Promise<AdminAuditListResponse<AdminAuditPostItem>> {
+  const res = await fetch(
+    `${API_BASE}/api/admin/users/${id}/posts?page=${page}`,
+    ssrInit(cookieHeaders(cookieHeader))
+  );
+  const data = await res.json().catch(() => ({}));
+  if (!res.ok) throw new Error(data.error || "获取帖子失败");
+  return data as AdminAuditListResponse<AdminAuditPostItem>;
+}
+
 export async function apiAdminUserAudit(id: number): Promise<AdminUserAuditProfile> {
   const res = await fetchWithRefresh(`/api/admin/users/${id}`, {
     headers: clientHeaders(),