fix(v2): 退款自愈扫描加回溯窗(防 LIMIT 尾部饥饿)+ 清死行

RefundApplyTask 的候选查询按 out_trade_no ASC/id ASC 取前 200,succeeded 退款历史
只增不减、partially_refunded 长期驻留,超过 limit 后最新的崩溃窗口永远排在候选外
扫不到。两路查询都加 since 回溯窗:RefundStore.ListDistinctOutTradeNosByStatusSince
(completed_at>=since)、OrderStore.ListOrdersByStatusSince(updated_at>=since),旧的
无窗方法原样保留。RefundApplyTask 新增 lookback/now 参数,config.ReconcileConfig 新增
RefundApplyLookbackMin(默认 48h)。顺带按 T6 复审补 OrderTTLMin 字段注释(须 ≫ crypto
orderTTL 15min),清 sync_test.go 死行 `_ = time.Second`。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013nMthbVEmQquxBRKb9Fj8u

internal/store/order_query.go

@@ -175,6 +175,22 @@ func (s *OrderStore) ListOrdersByStatus(statuses []model.OrderStatusV2, limit in
 	return out, nil
 }
 
+// ListOrdersByStatusSince 同 ListOrdersByStatus,但加 updated_at>=since 回溯窗——
+// refunding/partially_refunded 是长期驻留态(订单进入后可能停留很久),不设窗口时
+// 会占满 limit 名额,把「近期才卡滞、需要自愈」的订单挤出候选(与
+// RefundStore.ListDistinctOutTradeNosByStatusSince 同一治法,同一 lookback 语义)。
+func (s *OrderStore) ListOrdersByStatusSince(statuses []model.OrderStatusV2, since time.Time, limit int) ([]model.OrderV2, error) {
+	if limit <= 0 || limit > 500 {
+		limit = 200
+	}
+	var out []model.OrderV2
+	if err := s.db.Where("status IN ? AND updated_at >= ?", statuses, since).
+		Order("id ASC").Limit(limit).Find(&out).Error; err != nil {
+		return nil, fmt.Errorf("store.ListOrdersByStatusSince: %w", err)
+	}
+	return out, nil
+}
+
 // ListAttemptsByChannelSince 列某渠道 created_at>=since 的 attempt(任意状态),
 // 供 orphan 扫描构造"已知期望金额集"(凡 pay 合法签发过的金额都不算孤儿)。
 func (s *OrderStore) ListAttemptsByChannelSince(channel string, since time.Time, limit int) ([]model.Attempt, error) {