refactor: 统一状态名称映射为公共函数，清理废弃换卡/商户类型常量和模型

internal/service/commission_withdrawal/service.go

@@ -382,7 +382,7 @@ func (s *Service) buildWithdrawalRequestItem(r *model.CommissionWithdrawalReques
 		Fee:              r.Fee,
 		ActualAmount:     r.ActualAmount,
 		Status:           r.Status,
-		StatusName:       getWithdrawalStatusName(r.Status),
+		StatusName:       constants.GetWithdrawalStatusName(r.Status),
 		ShopID:           r.ShopID,
 		ShopName:         shopName,
 		ShopHierarchy:    shopHierarchy,
@@ -402,21 +402,6 @@ func (s *Service) buildWithdrawalRequestItem(r *model.CommissionWithdrawalReques
 	}
 }
 
-func getWithdrawalStatusName(status int) string {
-	switch status {
-	case constants.WithdrawalStatusPending:
-		return "待审核"
-	case constants.WithdrawalStatusApproved:
-		return "已通过"
-	case constants.WithdrawalStatusRejected:
-		return "已拒绝"
-	case constants.WithdrawalStatusPaid:
-		return "已到账"
-	default:
-		return "未知"
-	}
-}
-
 func containsSubstring(s, substr string) bool {
 	for i := 0; i <= len(s)-len(substr); i++ {
 		if s[i:i+len(substr)] == substr {