修复(#140): 去掉 cancelWithdrawalLogic 在新流程下的重复退款

HIF-22 把申请提现扣 commission 的逻辑移到审批时执行，但 cancel 路径漏改，
撤销 pending 提现仍调 UpdateCommission(+amount) 凭空给用户加佣金，并写出
一条 338 退佣金日志污染对账。

参照 rejectWithdrawal 的处理方式（withdrawalCommon.go:80-87），事务体只保留
withdrawal.status -> Cancelled 的更新，删除 UpdateCommission 与误导性的
WriteCommissionLog 调用。补单测覆盖 happy path、非 pending 状态短路、跨用户
撤销拒绝、与审批并发时 FOR UPDATE 行锁让 cancel 输掉 race 这四类场景。

Co-authored-by: multica-agent <github@multica.ai>

internal/logic/public/user/cancelWithdrawalLogic.go

@@ -4,7 +4,6 @@ import (
 	"context"
 
 	logicCommon "github.com/perfect-panel/server/internal/logic/common"
-	"github.com/perfect-panel/server/internal/model/log"
 	"github.com/perfect-panel/server/internal/model/user"
 	"github.com/perfect-panel/server/internal/svc"
 	"github.com/perfect-panel/server/internal/types"
@@ -57,13 +56,10 @@ func (l *CancelWithdrawalLogic) CancelWithdrawal(req *types.CancelWithdrawalRequ
 			return errors.Wrapf(xerr.NewErrCode(xerr.DatabaseUpdateError), "cancel withdrawal failed: %v", txErr)
 		}
 
-		if txErr = l.svcCtx.UserModel.UpdateCommission(l.ctx, withdrawal.UserId, withdrawal.Amount, tx); txErr != nil {
-			return errors.Wrapf(xerr.NewErrCode(xerr.DatabaseUpdateError), "refund commission failed: %v", txErr)
-		}
-
-		if txErr = logicCommon.WriteCommissionLog(tx, withdrawal.UserId, log.CommissionTypeWithdrawCancel, withdrawal.Amount, ""); txErr != nil {
-			return errors.Wrapf(xerr.NewErrCode(xerr.DatabaseInsertError), "write commission log failed: %v", txErr)
-		}
+		// Commission was NOT deducted at application time under the HIF-22
+		// approval flow, so cancellation requires no refund — only a status
+		// update. Refunding here would mint phantom commission and pollute
+		// reconciliation (mirrors rejectWithdrawal in admin/user/withdrawalCommon.go).
 
 		return nil
 	})