Surfaces videos.transcript_status (migration 007) on SummaryRow and adds
SetTranscriptStatus / GetTranscriptStatus / RateLimitedVideoIDs.
SetTranscriptStatus is the single choke point for the rate-limit lifecycle:
"rate_limited" stamps rate_limited_at = NOW(), every other status clears it,
so the runner's backoff window and the UI badge read one consistent source.
RateLimitedVideoIDs is the per-pass loader (mirrors SeenVideoIDs) the runner
uses to skip still-throttled videos without re-hitting the caption endpoint.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
