feat: 文件上传接口直接返回完整 URL + 提现 content 改为非必填

- FileUploadResponse / FileUploadCompleteResponse 精简为只返回 url
- S3Store.BuildObjectURL 拼接完整访问地址
- 提现 method=0 时 content 不再参与必填校验
- 新增用户端 API 接口文档

internal/logic/public/user/commissionWithdrawLogic.go

@@ -46,8 +46,8 @@ func (l *CommissionWithdrawLogic) CommissionWithdraw(req *types.CommissionWithdr
 			return nil, errors.Wrapf(xerr.NewErrCode(xerr.InvalidParams), "account is required for bank transfer")
 		}
 	default: // WithdrawalMethodOther
-		if req.Account == "" && req.Content == "" {
-			return nil, errors.Wrapf(xerr.NewErrCode(xerr.InvalidParams), "account or content is required for other methods")
+		if req.Account == "" {
+			return nil, errors.Wrapf(xerr.NewErrCode(xerr.InvalidParams), "account is required for other methods")
 		}
 	}