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

Squash merge of fix/140-去掉撤销提现的重复退款 (86896cd).

HIF-22 引入 rejectWithdrawal 反查支付网关后，cancelWithdrawalLogic 仍在
事务体内调用 UpdateCommission(+amount)，对已在 rejectWithdrawal 中退还
的金额做了二次退款。本次只保留 withdrawal.status -> Cancelled，与
rejectWithdrawal 行为对齐。

新增 cancelWithdrawalLogic_test.go 用 sqlmock 严格断言：撤销 happy path
只触发 BEGIN / SELECT FOR UPDATE / UPDATE withdrawals / COMMIT 四条 SQL,
对 user / system_logs 零读零写。

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
 	})