Job Expires At

Return when this job's downloadable files will be cleaned up.

Round-3 hostile-review T1-32 — the frontend polls this once on job-complete render so it can display a "Files available until Tue 24 Jun 07:00 UTC (in 6 days)" badge next to the download buttons. Previously users only saw an opaque 404 when a bookmarked link expired.

Response shape::

{
  "job_id":              "abc-123",
  "expires_at":          "2026-06-24T07:00:00Z",  # null if disabled
  "expires_in_seconds":  518400,                  # null if disabled
  "retention_days":      7,                       # 0 = cleanup disabled
}