fix(ad): 服务端强制不足一秒曝光收益为零 (#150)

## 改动
- eCPM 上报新增可选 exposure_ms，兼容旧客户端
- exposure_ms < 1000 时保留展示记录并强制有效 eCPM 为 0
- 失败领券任务允许保留短曝光零收益 trace，后台显示 0 而不是未填充
- 其他失败后的迟到曝光仍按原规则解绑 trace

## 验证
- 相关 pytest：10 passed
- Ruff：通过
- compileall：通过

依赖：先合并 Server #149。

---------

Co-authored-by: unknown <798648091@qq.com>
Reviewed-on: #150
Co-authored-by: linkeyu <linkeyu@wonderable.ai>
Co-committed-by: linkeyu <linkeyu@wonderable.ai>

app/api/v1/ad.py

@@ -281,7 +281,10 @@ def ecpm_report(payload: EcpmReportIn, user: CurrentUser, db: DbSession) -> Ecpm
     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
+        db,
+        feed_scene=payload.feed_scene,
+        trace_id=payload.trace_id,
+        exposure_ms=payload.exposure_ms,
     )
     if payload.trace_id and attributed_trace_id is None:
         logger.info(
@@ -296,11 +299,12 @@ def ecpm_report(payload: EcpmReportIn, user: CurrentUser, db: DbSession) -> Ecpm
         feed_scene=payload.feed_scene,
         trace_id=attributed_trace_id,
         app_env=payload.app_env, our_code_id=payload.our_code_id,
+        exposure_ms=payload.exposure_ms,
     )
     logger.info(
-        "ad ecpm report user_id=%d type=%s scene=%s session=%s ecpm=%s adn=%s slot=%s app=%s code=%s",
+        "ad ecpm report user_id=%d type=%s scene=%s session=%s ecpm=%s exposure_ms=%s adn=%s slot=%s app=%s code=%s",
         user.id, payload.ad_type, payload.feed_scene, payload.ad_session_id, payload.ecpm,
-        payload.adn, payload.slot_id, payload.app_env, payload.our_code_id,
+        payload.exposure_ms, payload.adn, payload.slot_id, payload.app_env, payload.our_code_id,
     )
     return EcpmReportOut(ok=True)