feat: 订单创建时快照买家手机号/昵称和套餐类型

新增字段：
- tb_order: buyer_phone, buyer_nickname（个人客户下单时快照）
- tb_order_item: package_type（套餐类型快照）

后台订单列表支持按 buyer_phone 精确过滤查询。

OpenSpec: order-buyer-snapshot

internal/store/postgres/order_store.go

@@ -136,6 +136,9 @@ func (s *OrderStore) List(ctx context.Context, opts *store.QueryOptions, filters
 	if v, ok := filters["identifier"]; ok {
 		query = query.Where("asset_identifier = ?", v)
 	}
+	if v, ok := filters["buyer_phone"]; ok {
+		query = query.Where("buyer_phone = ?", v)
+	}
 	if v, ok := filters["is_expired"]; ok {
 		isExpired, _ := v.(bool)
 		if isExpired {