支持客户、对话记录与统计报告 CSV 导出

- 新增 /customers/export、/sessions/export、/statistics/export
- 沿用列表筛选与角色可见范围，UTF-8 BOM 便于 Excel 打开
- 前端三处导出按钮接入真实下载

web/src/services/api.ts

@@ -1,4 +1,4 @@
-import { get, post, put, del, getList, postForm } from './request'
+import { get, post, put, del, getList, postForm, downloadFile } from './request'
 
 export interface LoginParams { username: string; password: string }
 export interface LoginResult { token: string; user_id: number; tenant_id: number; nickname: string; role: string }
@@ -253,6 +253,40 @@ export const getCustomers = (params?: { search?: string; status?: string; source
   if (params?.pageSize) search.set('pageSize', String(params.pageSize))
   return getList<Customer>(`/customers?${search}`)
 }
+
+export const exportCustomersCSV = (params?: { search?: string; status?: string; source?: string }) => {
+  const search = new URLSearchParams()
+  if (params?.search) search.set('search', params.search)
+  if (params?.status) search.set('status', params.status)
+  if (params?.source) search.set('source', params.source)
+  const qs = search.toString()
+  return downloadFile(`/customers/export${qs ? `?${qs}` : ''}`, `customers_${Date.now()}.csv`)
+}
+
+export const exportSessionsCSV = (params?: {
+  status?: string
+  priority?: string
+  agent_id?: number | string
+  channel_id?: number | string
+  search?: string
+  from?: string
+  to?: string
+}) => {
+  const search = new URLSearchParams()
+  if (params?.status) search.set('status', params.status)
+  if (params?.priority) search.set('priority', params.priority)
+  if (params?.agent_id != null && params.agent_id !== '') search.set('agent_id', String(params.agent_id))
+  if (params?.channel_id != null && params.channel_id !== '') search.set('channel_id', String(params.channel_id))
+  if (params?.search) search.set('search', params.search)
+  if (params?.from) search.set('from', params.from)
+  if (params?.to) search.set('to', params.to)
+  const qs = search.toString()
+  return downloadFile(`/sessions/export${qs ? `?${qs}` : ''}`, `sessions_${Date.now()}.csv`)
+}
+
+export const exportStatisticsCSV = () =>
+  downloadFile('/statistics/export', `statistics_${Date.now()}.csv`)
+
 export const getCustomer = (id: number) => get<{ customer: Customer; sessions: Session[] }>(`/customers/${id}`)
 export const createCustomer = (data: Partial<Customer>) => post<Customer>('/customers', data)
 export const updateCustomer = (id: number, data: Partial<Customer>) => put<Customer>(`/customers/${id}`, data)