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

server/internal/handler/widget.go

@@ -125,8 +125,13 @@ func (h *WidgetHandler) Init(c *gin.Context) {
 		return
 	}
 
+	setting, _ := getOrCreateTenantSettings(channel.TenantID)
+	withinWorkHours := isWithinWorkHours(setting, time.Now())
+	// 非工作时间不自动分配，走留言/排队提示
+	canServeNow := onlineCount > 0 && withinWorkHours
+
 	var assignedAgent *model.User
-	if onlineCount > 0 {
+	if canServeNow {
 		assignedAgent, err = tryAutoAssign(&session)
 		if err != nil {
 			c.JSON(http.StatusInternalServerError, gin.H{"code": 500, "message": "自动分配失败"})
@@ -138,22 +143,55 @@ func (h *WidgetHandler) Init(c *gin.Context) {
 		ws.DefaultHub.BroadcastToTenantStaff(session.TenantID, payload)
 	}
 
-	agentsOnline := onlineCount > 0
-	resp := gin.H{
-		"session_id":     session.ID,
-		"customer_id":    customer.ID,
-		"channel_id":     channel.ID,
-		"tenant_id":      channel.TenantID,
-		"visitor_token":  visitorToken,
-		"agents_online":  agentsOnline,
-		"session_status": session.Status,
+	welcome := defaultWelcomeMessage
+	offlinePrompt := offlineLeavePrompt
+	agentNickname := defaultAgentNickname
+	displayName := "在线客服"
+	worktimePrompt := defaultWorktimePrompt
+	if setting != nil {
+		if setting.WelcomeMessage != "" {
+			welcome = setting.WelcomeMessage
+		}
+		if setting.OfflinePrompt != "" {
+			offlinePrompt = setting.OfflinePrompt
+		}
+		if setting.AgentNickname != "" {
+			agentNickname = setting.AgentNickname
+		}
+		if setting.DisplayName != "" {
+			displayName = setting.DisplayName
+		}
+		if setting.WorktimePrompt != "" {
+			worktimePrompt = setting.WorktimePrompt
+		}
 	}
-	if !agentsOnline {
-		resp["offline_prompt"] = offlineLeavePrompt
+	// 非工作时间优先展示非工作时间提示
+	if !withinWorkHours {
+		offlinePrompt = worktimePrompt
+	}
+
+	resp := gin.H{
+		"session_id":         session.ID,
+		"customer_id":        customer.ID,
+		"channel_id":         channel.ID,
+		"tenant_id":          channel.TenantID,
+		"visitor_token":      visitorToken,
+		"agents_online":      canServeNow,
+		"online_agent_count": onlineCount,
+		"within_work_hours":  withinWorkHours,
+		"session_status":     session.Status,
+		"welcome_message":    welcome,
+		"display_name":       displayName,
+		"agent_nickname":     agentNickname,
+	}
+	if !canServeNow {
+		resp["offline_prompt"] = offlinePrompt
 	}
 	if assignedAgent != nil {
 		resp["agent_id"] = assignedAgent.ID
 		resp["agent_name"] = assignedAgent.Nickname
+	} else if canServeNow {
+		resp["agent_name"] = agentNickname
 	}
 
 	c.JSON(http.StatusOK, gin.H{"code": 0, "data": resp})