fix(ad): 失败领券任务不再归属迟到广告收益 (#149)

## 修复内容
- coupon 广告上报到达时校验对应领券 session 状态
- session 已 failed 时保留全局广告收益记录，但清空 trace 归属，失败明细不再显示收益
- 增加失败 trace、其他场景和未知 trace 的回归测试

## 验证
- 相关 pytest：7 passed
- Ruff：通过
- compileall：通过

---------

Co-authored-by: unknown <798648091@qq.com>
Reviewed-on: #149
Co-authored-by: linkeyu <linkeyu@wonderable.ai>
Co-committed-by: linkeyu <linkeyu@wonderable.ai>

app/api/v1/ad.py

@@ -280,13 +280,21 @@ def ecpm_report(payload: EcpmReportIn, user: CurrentUser, db: DbSession) -> Ecpm
     Bearer 鉴权,user_id 取自 JWT(不信 body)。best-effort:落库即 ok,客户端 fire-and-forget,
     丢一两条不影响业务(穿山甲后台报表是结算权威)。eCPM 与发奖(S2S)是两条独立流,不逐条关联。
     """
+    attributed_trace_id = crud_ecpm.attributable_trace_id(
+        db, feed_scene=payload.feed_scene, trace_id=payload.trace_id
+    )
+    if payload.trace_id and attributed_trace_id is None:
+        logger.info(
+            "detach late coupon ad impression from failed trace user_id=%d trace=%s session=%s",
+            user.id, payload.trace_id, payload.ad_session_id,
+        )
     crud_ecpm.create_ecpm_record(
         db, user.id,
         ad_type=payload.ad_type, ecpm_raw=payload.ecpm,
         ad_session_id=payload.ad_session_id,
         adn=payload.adn, slot_id=payload.slot_id,
         feed_scene=payload.feed_scene,
-        trace_id=payload.trace_id,
+        trace_id=attributed_trace_id,
         app_env=payload.app_env, our_code_id=payload.our_code_id,
     )
     logger.info(