fix(ai-ops): HealLog DetachedInstanceError — expunge after commit

session.close() 後存取 heal_log.result 觸發 lazy reload 失敗。
在 close 前 expunge(hl) 讓物件帶著已載入屬性脫離 session。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/auto_heal_service.py

@@ -373,6 +373,7 @@ class AutoHealService:
             )
             session.add(hl)
             session.commit()
+            session.expunge(hl)  # detach after commit to keep loaded attrs
             return hl
         except Exception as e:
             session.rollback()