- A failure keeps its traceback unless it is yt-dlp's or our own StatedFailure (a
message that is the whole story). A plain RuntimeError, RecursionError or OSError
is also what a bug of ours raises, and its stack is the only lead.
- The stack is scrubbed link by link (logs.scrubbed_stack): a chained DownloadError
under a DB error no longer prints yt-dlp's text unscrubbed.
- Engine hide_parameters: a DB error's message no longer carries the title or path
it was writing.
- The download and edit failure lines go out even when their DB write fails.
- The worker's child_exit/crash/supervisor lines say download.job.failed only when
the job failed there; a crash the DB will not record no longer ends the thread.
Stopping a paused child is download.child.stopped, not a second abort.
- log_safe also covers generic ids with spaces, playlist titles and bare ids.
- The ffmpeg image steps log the failure kind, not the argv with its path.
- The consent contract accepts only the body of a plain consented_trace() check,
and any level that may be TRACE.
- Tests for each; every one mutation-checked.
