Three UX improvements for the pending-transcript state:
1. Summarized videos sort to top (ORDER BY (s.id IS NOT NULL) DESC, seen_at DESC)
so completed summaries are always immediately visible without filtering.
ListVideos default limit raised from 50 to 500 to show the full backlog.
2. Pipeline stats bar above the video list: '2 summarized · 256 fetching soon · 12
no captions' — computed from the unfiltered row set, hidden when everything is
summarized.
3. 'Try now' button on rate-limited cards replaces the passive 'Retrying later'
chip. POST /v/{id}/retry-now clears rate_limited_at then calls ProcessVideo
through the shared globalFetchGate — same rate limiting as the scheduler, safe
under concurrent use.