Match re-render previously showed only a frozen text status. Now:
- _stage_videos_render reports per-clip start/end via clip_cb and overall
  done/total via progress_cb.
- _run_match_job seeds an items list and maps clip state into the job record.
- The match detail page renders a global progress bar plus one bar per
  clip/output (pending/rendering/done/failed), and these survive a reload
  via /active-jobs + resumeMatchJobs.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>