feat: implement withdrawal improvements P01-P05

- P04: fix Withdrawal.TableName() to return 'withdrawals'
- P03: add WithdrawalStatus* and WithdrawalMethod* constants; replace magic numbers; add CommissionTypeWithdrawCancel=338
- P01: add POST /v1/public/user/withdrawal_cancel to cancel pending withdrawals with ownership check, row lock, commission refund, and audit log
- P02: add method/account/qr_code_url fields to Withdrawal model and API; add input validation (qr_code_url required for Alipay/Wechat, account required for bank)
- P05: add method filter to admin GET /v1/admin/user/withdrawal/list

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

internal/types/types.go

@@ -289,8 +289,11 @@ type CommissionLog struct {
 }
 
 type CommissionWithdrawRequest struct {
-	Amount  int64  `json:"amount"`
-	Content string `json:"content"`
+	Amount    int64  `json:"amount"`
+	Content   string `json:"content"`
+	Method    uint8  `json:"method" validate:"oneof=0 1 2 3"`
+	Account   string `json:"account,omitempty"`
+	QrCodeUrl string `json:"qr_code_url,omitempty"`
 }
 
 type ConnectionRecords struct {
@@ -2274,6 +2277,10 @@ type QueryUserSubscribeNodeListResponse struct {
 	List []UserSubscribeInfo `json:"list"`
 }
 
+type CancelWithdrawalRequest struct {
+	WithdrawalId int64 `json:"withdrawal_id" validate:"required,gt=0"`
+}
+
 type QueryWithdrawalLogListRequest struct {
 	Page int `form:"page"`
 	Size int `form:"size"`
@@ -2289,6 +2296,7 @@ type GetWithdrawalListRequest struct {
 	Size   int    `form:"size"`
 	UserId *int64 `form:"user_id,omitempty"`
 	Status *uint8 `form:"status,omitempty"`
+	Method *uint8 `form:"method,omitempty"`
 }
 
 type GetWithdrawalListResponse struct {
@@ -3607,6 +3615,9 @@ type WithdrawalLog struct {
 	Content   string `json:"content"`
 	Status    uint8  `json:"status"`
 	Reason    string `json:"reason,omitempty"`
+	Method    uint8  `json:"method"`
+	Account   string `json:"account"`
+	QrCodeUrl string `json:"qr_code_url"`
 	CreatedAt int64  `json:"created_at"`
 	UpdatedAt int64  `json:"updated_at"`
 }