gallery-dl logs `[download][error] Failed to download <file>.part` when a
single post attachment's media URL expires or is deleted, then recovers
and proceeds with the rest of the run. Our error categorizer was letting
a urllib3 debug line like `"HEAD /media-u/v3/<id> HTTP/1.1" 404 0` match
the NOT_FOUND_PATTERNS list, flagging the whole source as deleted even
though gallery-dl kept downloading subsequent items successfully.
Adds "failed to download" to the per-item allowlist so the mask flips
when skip activity is present, matching the shape of the campaign-ID
fix. Total-failure runs still classify as failures.
Also renames the Download Details modal's "Error Log" panel to
"Verbose Log (stderr)" — gallery-dl's `-v` flag sends all logging
(including [debug] lines) to stderr, so the original label was
misleading. Drops the blanket red text color for the same reason.
bvandeusen
edbb349c58