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

reaction_board/web/static/style.css

@@ -510,6 +510,7 @@ a.live-chip:hover { border-color: color-mix(in srgb, var(--accent) 55%, var(--bo
 .status-grid strong { display: block; margin-top: 2px; font-size: 12.5px; font-weight: 600; }
 /* 预计下次运行等 3 项：PC 与移动端都保持一行 */
 .status-grid.status-row-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
+.status-grid.status-row-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
 
 .segmented {
   display: inline-flex;
@@ -993,4 +994,4 @@ a.live-chip:hover { border-color: color-mix(in srgb, var(--accent) 55%, var(--bo
 .about-page .panel h2 { font-size: 15px; margin-bottom: 8px; }
 .about-list { margin: 0; padding-left: 18px; display: grid; gap: 6px; font-size: 13px; line-height: 1.55; }
 .about-list code { padding: 1px 4px; border-radius: 4px; background: var(--accent-soft); font-size: 12px; }
-.about-list.about-weights { list-style: none; padding-left: 0; grid-template-columns: repeat(2, minmax(0, 1fr)); }
+.about-list.about-weights { list-style: none; padding-left: 0; grid-template-columns: repeat(2, minmax(0, 1fr)); }