新功能(#26): 拆分退款日志查询接口

拆分用户中心退款日志查询：

- 新增 GET /v1/public/user/commission_return_log（333/337/338）
- 旧 GET /v1/public/user/withdrawal_log?biz_type=commission_refund 复用新逻辑做兼容
- 默认 withdrawal_log 行为不变（仍查 withdrawals 表）
- 单测覆盖 333/337/338 happy path、坏 JSON 跳过、object_id 隔离、handler 级 HTTP 响应

父 issue: HIF-25
子 issue: HIF-26

internal/types/types.go

@@ -309,6 +309,16 @@ type CommissionLog struct {
 	Timestamp int64  `json:"timestamp"`
 }
 
+type CommissionReturnLog struct {
+	Id        int64  `json:"id"`
+	UserId    int64  `json:"user_id"`
+	Amount    int64  `json:"amount"`
+	EventType uint16 `json:"event_type"`
+	Content   string `json:"content"`
+	CreatedAt int64  `json:"created_at"`
+	UpdatedAt int64  `json:"updated_at"`
+}
+
 type CommissionWithdrawRequest struct {
 	Amount    int64  `json:"amount"`
 	Content   string `json:"content"`
@@ -2376,6 +2386,16 @@ type QueryAnnouncementResponse struct {
 	List  []Announcement `json:"announcements"`
 }
 
+type QueryCommissionReturnLogRequest struct {
+	Page int `form:"page"`
+	Size int `form:"size"`
+}
+
+type QueryCommissionReturnLogResponse struct {
+	List  []CommissionReturnLog `json:"list"`
+	Total int64                 `json:"total"`
+}
+
 type QueryDocumentDetailRequest struct {
 	Id int64 `form:"id" validate:"required"`
 }