修复(#4): 奖品更新支持修改 type（原来 type 被静默忽略）

UpdateLotteryPrize 之前可改字段漏了 type，导致 PUT 带 type 不生效、
只能删了重建。补上 UpdateAdminLotteryPrizeRequest.Type + fields["type"]。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/logic/admin/lottery/lottery.go

@@ -518,6 +518,9 @@ func (l *UpdateLotteryPrizeLogic) UpdateLotteryPrize(req *types.UpdateAdminLotte
 		if req.Slot != nil {
 			fields["slot"] = *req.Slot
 		}
+		if req.Type != "" {
+			fields["type"] = req.Type
+		}
 		if req.Name != "" {
 			fields["name"] = req.Name
 		}

internal/types/lottery.go

@@ -266,6 +266,7 @@ type CreateAdminLotteryPrizeRequest struct {
 type UpdateAdminLotteryPrizeRequest struct {
 	Id         int64           `path:"id" json:"-" validate:"required"`
 	Slot       *int            `json:"slot,omitempty"`
+	Type       string          `json:"type,omitempty"`
 	Name       string          `json:"name,omitempty"`
 	IconUrl    string          `json:"icon_url,omitempty"`
 	Config     json.RawMessage `json:"config,omitempty"`