feat(ad): eCPM 上报接口 + 冷却策略解耦纯函数 + savings JSONB 跨库修复

- 新增 POST /api/v1/ad/ecpm-report:激励视频展示后客户端上报本次 eCPM,落 ad_ecpm_record 做内部收益统计(model/repository/schema/alembic 迁移 + 接口文档)
- 看广告冷却策略抽到 app/core/ad_cooldown.py 纯函数;ad_reward.today_status 只取数据,换策略只改这一处
- savings.dishes 改 JSON().with_variant(JSONB,"postgresql"):SQLite 无 visit_JSONB 会让 create_all 编译崩,修复后测试套件恢复

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/api/v1/ad.py

@@ -19,8 +19,15 @@ from app.core import rewards
 from app.core.config import settings
 from app.integrations import pangle
 from app.core.ratelimit import rate_limit
+from app.repositories import ad_ecpm as crud_ecpm
 from app.repositories import ad_reward as crud_ad
-from app.schemas.ad import AdRewardStatusOut, PangleCallbackOut, TestGrantOut
+from app.schemas.ad import (
+    AdRewardStatusOut,
+    EcpmReportIn,
+    EcpmReportOut,
+    PangleCallbackOut,
+    TestGrantOut,
+)
 
 logger = logging.getLogger("shagua.ad")
 
@@ -95,6 +102,30 @@ def reward_status(user: CurrentUser, db: DbSession) -> AdRewardStatusOut:
     )
 
 
+@router.post(
+    "/ecpm-report",
+    response_model=EcpmReportOut,
+    summary="上报本次广告展示的 eCPM(内部收益统计)",
+    dependencies=[Depends(rate_limit(120, 60, "ad-ecpm-report"))],
+)
+def ecpm_report(payload: EcpmReportIn, user: CurrentUser, db: DbSession) -> EcpmReportOut:
+    """客户端在广告展示后(onAdShow 读 getShowEcpm)上报 eCPM,落库做内部收益统计/对账。
+
+    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。
+    """
+    crud_ecpm.create_ecpm_record(
+        db, user.id,
+        ad_type=payload.ad_type, ecpm_raw=payload.ecpm,
+        adn=payload.adn, slot_id=payload.slot_id,
+    )
+    logger.info(
+        "ad ecpm report user_id=%d type=%s ecpm=%s adn=%s slot=%s",
+        user.id, payload.ad_type, payload.ecpm, payload.adn, payload.slot_id,
+    )
+    return EcpmReportOut(ok=True)
+
+
 @router.post(
     "/test-grant",
     response_model=TestGrantOut,