- 入参 referrerApp、referrerUserId 同时传才写入 order_source，否则落库空串
- 列表/详情 VO 返回 referrerApp、referrerUserId，老数据兼容空串
- DDL: docu/order_referrer_kylin.sql
Co-authored-by: Cursor <cursoragent@cursor.com>