欢迎语支持多段配置与图片

租户可配置有序文本/图片欢迎语；设置页支持增删排序与上传，Widget 空会话按序展示；兼容旧 welcome_message 字段。

server/internal/handler/widget.go

@@ -148,15 +148,13 @@ func (h *WidgetHandler) Init(c *gin.Context) {
 		ws.DefaultHub.BroadcastToTenantStaff(session.TenantID, payload)
 	}
 
-	welcome := defaultWelcomeMessage
+	welcomeSegs := resolveWelcomeSegments(setting)
+	welcome := firstWelcomeText(welcomeSegs)
 	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
 		}
@@ -186,6 +184,7 @@ func (h *WidgetHandler) Init(c *gin.Context) {
 		"within_work_hours":  withinWorkHours,
 		"session_status":     session.Status,
 		"welcome_message":    welcome,
+		"welcome_messages":   welcomeSegs,
 		"display_name":       displayName,
 		"agent_nickname":     agentNickname,
 	}