实现租户系统设置落库：欢迎语、工作时间与通知开关

- 新增 TenantSetting 模型与 /api/settings 读写接口
- 设置页接通基本资料、自动回复、工作时间、通知偏好
- Widget 初始化使用欢迎语/离线提示，非工作时间不自动分配
- 补充设置持久化与 Widget 提示集成测试

web/src/services/api.ts

@@ -142,6 +142,25 @@ export const getChannels = () => get<Channel[]>('/channels')
 export const createChannel = (data: { type: string; name?: string }) => post<Channel>('/channels', data)
 export const updateChannel = (id: number, data: { name?: string; status?: string }) => put<Channel>(`/channels/${id}`, data)
 
+// Tenant settings
+export type WorkHours = Record<string, string>
+export interface TenantSettings {
+  tenant_id: number
+  display_name: string
+  agent_nickname: string
+  timezone: string
+  welcome_message: string
+  offline_prompt: string
+  work_hours: WorkHours
+  worktime_prompt: string
+  notify_new_session: boolean
+  notify_offline_leave: boolean
+  notify_daily_report: boolean
+}
+export const getTenantSettings = () => get<TenantSettings>('/settings')
+export const updateTenantSettings = (data: Partial<TenantSettings> & { work_hours?: WorkHours }) =>
+  put<TenantSettings>('/settings', data)
+
 // Statistics
 export const getKPIs = () => get<StatisticsKpis>('/statistics/kpi')
 export const getSessionTrend = (period: 'today' | 'day' | 'month' = 'day') => get<{ date: string; count: number }[]>(`/statistics/trend?period=${period}`)