fix(退款): 修复创建退款申请插入审批尝试记录失败

创建路径把审批尝试记录在事务外预构造后原样插入，缺失只能在事务内生成的
attempt_no 与 package_usage_snapshot，触发 NOT NULL 与 CHECK 约束，
接口统一返回 2002 数据库错误（5xx 脱敏掩盖了具体消息）。

- 尝试记录收敛为事务内唯一构造点 buildAttempt，CreateCommand 与
  ResubmitCommand 只传按冻结商户派生的渠道退款请求号
- TriggerHistorical 补上缺失的尝试记录插入，此前 attempt.ID 恒为 0，
  必然以「关联已变化」冲突收场
- 按「首次接入企业微信审批的实例」语义回写
  tb_refund_request.approval_instance_id，恢复本地人工终审的 IS NULL
  防重保护与退款导出投影

internal/service/refund/method.go

@@ -254,20 +254,12 @@ func validateFrozenRefundAmount(amount, frozenActualReceivedAmount int64) error
 	return nil
 }
 
-// buildAttemptFromDecision 依据方式判定结果构造一条不可变审批尝试记录。
-func buildAttemptFromDecision(decision *refundMethodDecision, refund *model.RefundRequest, config *model.WechatConfig, now time.Time) *model.RefundRequestAttempt {
-	attempt := &model.RefundRequestAttempt{
-		RefundID:                   refund.ID,
-		Method:                     refund.Method,
-		RefundAmount:               refund.RequestedRefundAmount,
-		FrozenActualReceivedAmount: decision.FrozenActualReceivedAmount,
-		RefundReason:               refund.RefundReason,
-		CustomerAccountInfo:        refund.CustomerAccountInfo,
-		CustomerVoucherKeys:        refund.RefundVoucherKey,
-		SubmittedByAccountID:       refund.Creator,
+// buildChannelRefundRequestNo 仅在原路退款方式下按冻结商户派生本次尝试的渠道退款请求号。
+// 请求号由收口审批申请用例冻结到不可变尝试记录上，同一尝试的渠道重试复用它作为幂等标识，
+// 重提生成新值；非原路方式返回空串。
+func buildChannelRefundRequestNo(method string, config *model.WechatConfig) string {
+	if method != constants.RefundMethodOriginalRoute {
+		return ""
 	}
-	if refund.Method == constants.RefundMethodOriginalRoute {
-		attempt.ChannelRefundRequestNo = requestChannelRefundNo(config, now)
-	}
-	return attempt
+	return requestChannelRefundNo(config, time.Now())
 }