perf(core): 资产预览改 TOS 公读直链 + 通知只取首页,减刷新开销与缓存失效

- 资产 preview_url 从「逐图签发预签名 URL」改为虚拟主机式公读直链
  (https://{bucket}.{host}/{key})。桶公读已验证免签可访问;直链稳定可被浏览器/CDN
  缓存,而签名链每次都变、1h 过期反而打不到缓存。boto3 也移出序列化热路径。
- allNotifications 不再逐页翻全部(原 O(N) 随消息增长拖慢每次刷新),只取首页 100 条
  (侧边栏徽标 unread_count + 团队动态仅展示最近 6 条已足够);「共 N」改用后端真实 count。
- perf-probe:page_size 由 API 级硬闸确定性守住后,浏览器端「资产翻页」降为提示
  (翻 1~2 页是资产真超 200 的合法分页,仅 ≥3 页才疑似 page_size 失效)。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/frontend/src/routes/team.tsx

@@ -27,12 +27,13 @@ const PERM_ROWS: Array<{ cap: string; cells: [string, string, string]; last?: bo
   { cap: "创建项目 / 用 AI 流程", cells: ["✓", "✓", "✓"], last: true }
 ];
 
-export function TeamPage({ team, user, members, billing, notifications = [], navigate, onCreateMember, onUpdateMember, onRemoveMember, onResetPassword, onRecharge }: {
+export function TeamPage({ team, user, members, billing, notifications = [], notificationTotal, navigate, onCreateMember, onUpdateMember, onRemoveMember, onResetPassword, onRecharge }: {
   team: Team;
   user: User;
   members: TeamMember[];
   billing: BillingSummary | null;
   notifications?: Notification[];
+  notificationTotal?: number; // 后端真实总数(只加载了近期 100 条,「共 N」用这个而非数组长度)
   navigate: (page: Page) => void;
   onCreateMember: (payload: { username: string; password: string; name?: string; role?: string; monthly_credit_limit?: number }) => void | Promise<unknown>;
   onUpdateMember: (id: string, payload: { role?: string; monthly_credit_limit?: number }) => void | Promise<unknown>;
@@ -211,7 +212,7 @@ export function TeamPage({ team, user, members, billing, notifications = [], nav
         <div className="team-feed">
           <div className="h">
             <h3>团队动态</h3>
-            <span className="ct">// 最近 {Math.min(feedItems.length, 6)} 条 · 共 {notifications.length}</span>
+            <span className="ct">// 最近 {Math.min(feedItems.length, 6)} 条 · 共 {notificationTotal ?? notifications.length}</span>
             <a className="more" id="open-feed-all" role="button" tabIndex={0} onClick={() => navigate("messages")}>全部 →</a>
           </div>
           <div className="feed-list">