修正默认客服分配逻辑

backend/internal/modules/systemconfig/repository.go

@@ -34,7 +34,7 @@ var defaultConfigs = []defaultConfig{
 	{Key: listingPublishAgreementsConfigKey, Value: defaultListingPublishAgreementsConfigValue(), Description: "发布账号前协议配置 JSON"},
 	{Key: orderAgreementsConfigKey, Value: defaultOrderAgreementsConfigValue(), Description: "下单前协议配置 JSON"},
 	{Key: postRentalNoticeConfigKey, Value: defaultPostRentalNoticeConfigValue(), Description: "租后须知配置 JSON"},
-	{Key: "chat.default_support_admin_id", Value: "1", Description: "订单群聊回退客服 ID（仅当无可用客服时使用）"},
+	{Key: "chat.default_support_admin_id", Value: "2", Description: "默认客服 ID（必须是启用状态的客服角色）"},
 	{Key: "chat.auto_welcome_message", Value: "欢迎加入订单群聊！如有任何问题，请随时沟通。", Description: "建群后自动发送的欢迎话术"},
 	{Key: homeAnnouncementsConfigKey, Value: defaultHomeAnnouncementsConfigValue(), Description: "移动端首页公告 JSON 数组"},
 	{Key: homeBannersConfigKey, Value: defaultHomeBannersConfigValue(), Description: "移动端首页轮播图 JSON 数组"},
@@ -150,7 +150,7 @@ func (r *Repository) ensureDefaults() error {
 				return err
 			}
 			if item.Key == "chat.default_support_admin_id" {
-				if err := updateDefaultDescription(tx, item); err != nil {
+				if err := updateDefaultSupportConfig(tx, item); err != nil {
 					return err
 				}
 			}
@@ -164,15 +164,23 @@ func (r *Repository) ensureDefaults() error {
 	})
 }
 
-func updateDefaultDescription(tx *gorm.DB, item defaultConfig) error {
+func updateDefaultSupportConfig(tx *gorm.DB, item defaultConfig) error {
 	var row model.SystemConfig
 	if err := tx.Where("`key` = ?", item.Key).First(&row).Error; err != nil {
 		return err
 	}
-	if row.Description == item.Description {
+	changed := false
+	if strings.TrimSpace(row.Value) == "1" {
+		row.Value = item.Value
+		changed = true
+	}
+	if row.Description != item.Description {
+		row.Description = item.Description
+		changed = true
+	}
+	if !changed {
 		return nil
 	}
-	row.Description = item.Description
 	return tx.Save(&row).Error
 }