The native client treated a gallery image without `file_name` as schema drift
and raised "Patreon API changed — ingester needs update", failing the whole walk
(operator-flagged 2026-06-07: BlenderKnight post 73665615, kind=images). But the
resource had a valid URL, and the code already derives a filename from the URL
basename right below the raise — the same fallback gallery-dl uses. Patreon
legitimately serves some images without file_name, so this isn't drift.
Drop the require_file_name gate from _media_item: file_name is now optional for
every kind (images/attachments/postfile), falling back to the URL basename.
Genuine drift still raises — no resolvable URL, or a media id referenced by a
relationship but absent from `included`. Test updated to assert the fallback.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>