feat(sale): 新增销售合同效益测算审核功能

- 在 append.go 中添加 AuditBenefit 方法，用于审核效益测算
- 在 audit.go 中添加 Benefit 方法，用于效益测算审核
- 在 constant.go 中添加 BusinessTypeSaleBenefitAudit常量，用于标识销售合同效益测算审核业务类型

erp/constant.go

@@ -6,6 +6,7 @@ const (
 	BusinessTypeSaleAuditClose      BusinessType = "saleAuditClose"      // 销售合同关单审核
 	BusinessTypeSaleAppendAudit     BusinessType = "saleAuditAppend"     // 销售合同追加商品
 	BusinessTypeSaleChangeAudit     BusinessType = "saleAuditChange"     // 销售合同修改产品
+	BusinessTypeSaleBenefitAudit    BusinessType = "saleAuditBenefit"    // 销售合同修改效益测算
 	BusinessTypePurchaseAudit       BusinessType = "purchaseAudit"       // 采购合同审核
 	BusinessTypeShipmentAudit       BusinessType = "shipmentAudit"       // 订舱单审核
 	BusinessTypeShipmentModifyAudit BusinessType = "shipmentModifyAudit" // 订舱单修改单审核