feat(growth): same-day 1-day baselines for new videos

Let 1-day view growth use a zero baseline for videos published today, and the first successful sample for older videos ingested today, without mixing those into 7/30-day rankings.

reaction_board/services/snapshot.py

@@ -310,7 +310,8 @@ class SnapshotService:
         """刷新近 N 天新视频的当日快照；不碰完成日标记与日备份。
 
         「近 N 天」按 pubdate 墙钟窗口：``now - recent_video_days * 86400``，
-        不是上海日历日差。允许覆盖同日已有 ``ok=1`` 行以便小时级刷新。
+        不是上海日历日差。当天入库但发布更早的旧片不进小时任务。
+        允许覆盖同日已有 ``ok=1`` 行以便小时级刷新。
         """
         cfg = self.config_store.get()
         client = self._client()