fix(admin): 通知分页、登录过期提示、附件打开反馈与导出统一 loading

- 通知中心改为游标分页 + 加载更多,历史通知不再被 50 条上限截断;
  加载失败显示错误态与重试
- AI 流式请求 401 被登出时,登录页提示"登录已过期",不再无声踢出
- AI 附件/引用来源打开失败时给出明确错误提示,不再"点了没反应"
- 新增 useDownload hook:统一导出/下载的防重复、loading 与成功/失败反馈;
  接入学生/账单/房间/入住/费用五个页面的模板下载与导出按钮
- 学生页移除不检查响应状态的私有下载实现,统一走 downloadBlob

apps/admin/src/components/AiChat/AiMessageContent.tsx

@@ -13,6 +13,7 @@ import type { ThoughtChainItemType } from '@ant-design/x';
 import XMarkdown, { type ComponentProps } from '@ant-design/x-markdown';
 import { Alert, Button, Flex, Input, Space, Typography } from 'antd';
 import { useUserStore } from '../../store/user/userStore';
+import { message } from '../../ui/app-message';
 import { DynamicChart } from './DynamicChart';
 import { DynamicForm } from './DynamicForm';
 import { DynamicReview } from './DynamicReview';
@@ -104,6 +105,24 @@ async function openSourceUrl(item: { url?: string }): Promise<void> {
   window.setTimeout(() => URL.revokeObjectURL(objectUrl), 60_000);
 }
 
+/** 打开附件，失败时给出明确提示（避免「点了没反应」） */
+async function handleOpenAttachment(attachment: AiAttachment): Promise<void> {
+  try {
+    await openAttachment(attachment);
+  } catch (error: unknown) {
+    message.error(error instanceof Error ? error.message : '附件打开失败，请重试');
+  }
+}
+
+/** 打出来源链接，失败时给出明确提示 */
+async function handleOpenSource(item: { url?: string }): Promise<void> {
+  try {
+    await openSourceUrl(item);
+  } catch (error: unknown) {
+    message.error(error instanceof Error ? error.message : '来源打开失败，请重试');
+  }
+}
+
 function ToolChain({ tools }: { tools: AiToolRun[] }) {
   const items = useMemo<ThoughtChainItemType[]>(
     () =>
@@ -228,7 +247,7 @@ export const AiMessageContent: React.FC<AiMessageContentProps> = ({
       byte={attachment.size}
       size="small"
       icon={attachmentIcon(attachment)}
-      onClick={() => void openAttachment(attachment)}
+      onClick={() => void handleOpenAttachment(attachment)}
     />
   ));
 
@@ -352,7 +371,7 @@ export const AiMessageContent: React.FC<AiMessageContentProps> = ({
         <Sources
           items={sourceItems}
           title="引用来源"
-          onClick={(item) => void openSourceUrl(item as { url?: string })}
+          onClick={(item) => void handleOpenSource(item as { url?: string })}
         />
       )}
       {(message.forms ?? []).map((form) => (