feat: home growth auto(7→1) and hourly recent-video snapshot

- Add analytics.home_growth_days (auto|1|7); API growth_days=auto tries 7 then 1
- Homepage shows active window and growth-board link; clearer empty reason
- New snapshot_recent scheduler task (schedule.recent_snapshot_minutes/days)
- run_recent_videos refreshes new aids only; never touches completed/backup
- Full 00:01 job keeps ok=1 skip (covers hourly refresh within 1h); mutex with recent

tests/web_fixtures.py

@@ -50,6 +50,8 @@ def write_config(
             "discover_minutes": 60,
             "snapshot_at": "00:01",
             "candidate_ttl_days": 7,
+            "recent_snapshot_minutes": 60,
+            "recent_video_days": 2,
         },
     }, ensure_ascii=False, indent=2), encoding="utf-8")
     return path