fix(fin): 提现拒绝补 remark 必填校验 FIN-02

- CommissionWithdrawalHandler 新增 validator 字段
- RejectWithdrawal 在 BodyParser 后补充 validator.Struct 参数验证，确保 remark 必填

internal/handler/admin/commission_withdrawal.go

@@ -3,6 +3,7 @@ package admin
 import (
 	"strconv"
 
+	"github.com/go-playground/validator/v10"
 	"github.com/gofiber/fiber/v2"
 
 	"github.com/break/junhong_cmp_fiber/internal/model/dto"
@@ -11,12 +12,15 @@ import (
 	"github.com/break/junhong_cmp_fiber/pkg/response"
 )
 
+// CommissionWithdrawalHandler 提现申请管理处理器
 type CommissionWithdrawalHandler struct {
-	service *commissionWithdrawalService.Service
+	service   *commissionWithdrawalService.Service
+	validator *validator.Validate
 }
 
-func NewCommissionWithdrawalHandler(service *commissionWithdrawalService.Service) *CommissionWithdrawalHandler {
-	return &CommissionWithdrawalHandler{service: service}
+// NewCommissionWithdrawalHandler 创建提现申请管理处理器
+func NewCommissionWithdrawalHandler(service *commissionWithdrawalService.Service, validator *validator.Validate) *CommissionWithdrawalHandler {
+	return &CommissionWithdrawalHandler{service: service, validator: validator}
 }
 
 func (h *CommissionWithdrawalHandler) ListWithdrawalRequests(c *fiber.Ctx) error {
@@ -62,6 +66,9 @@ func (h *CommissionWithdrawalHandler) RejectWithdrawal(c *fiber.Ctx) error {
 	if err := c.BodyParser(&req); err != nil {
 		return errors.New(errors.CodeInvalidParam, "请求参数解析失败")
 	}
+	if err := h.validator.Struct(&req); err != nil {
+		return errors.New(errors.CodeInvalidParam)
+	}
 
 	result, err := h.service.Reject(c.UserContext(), uint(id), &req)
 	if err != nil {