fix(admin): UX improvements — silent fetch failures, empty states, batch loading guards, dashboard refresh

- Replace console.error-only catches with message.error user-facing notifications
  across Bills, Classes, ClassroomRentals, ClassroomSchedule, Classrooms, Deposits,
  Expenses, OperationLogs, Permissions, Roles, RoomVisual, Rooms, Students,
  Tenants, Users
- Add Empty component via Table locale prop on list pages: Bills, Classes,
  ClassroomRentals, Classrooms, Deposits, Expenses (room+personal), Occupancies,
  Rooms, Students, Tenants, Roles
- Add batchLoading state to batch delete/update operations: Bills (batchDelete,
  batchUpdateStatus), Expenses (batchDeleteRoom, batchDeletePersonal),
  Occupancies (batchCheckOut, batchDelete), Rooms (batchDelete),
  Students (batchDelete)
- Add refreshLoading indicator to Dashboard header when re-fetching data
- Consistent error pattern: catch (e: unknown) { const err = e as { message?: string }; message.error(...); }

apps/admin/src/pages/Classes/index.tsx

@@ -1,7 +1,7 @@
 import React, { useEffect, useState, useMemo, useCallback } from 'react';
 import {
   Table, Button, Input, Select, Space, Tag, Modal, Form, InputNumber,
-  DatePicker, Popconfirm, message, Card, Switch,
+  DatePicker, Popconfirm, message, Card, Switch, Empty,
 } from 'antd';
 import type { ColumnsType } from 'antd/es/table';
 import { PlusOutlined, SearchOutlined, TeamOutlined, InboxOutlined } from '@ant-design/icons';
@@ -98,8 +98,9 @@ const ClassesPage: React.FC = () => {
       params.isArchived = showArchived;
       const res = await api.get<ClassItem[]>('/classes', { params } as Record<string, unknown>);
       setData(res);
-    } catch (e) {
-      console.error(e);
+    } catch (e: any) {
+      message.error(e?.message || '加载失败，请稍后重试');
+    }
     } finally {
       setLoading(false);
     }
@@ -266,6 +267,7 @@ const ClassesPage: React.FC = () => {
         dataSource={filtered}
         rowKey="id"
         loading={loading}
+        locale={{ emptyText: <Empty description="暂无数据" /> }}
         pagination={{ pageSize: 20 }}
         scroll={{ x: 1100 }}
       />