Salvaged from #59742 (downloads half only). Main already resolves the
event-level team id from the channel→workspace cache before downloads
(the file-EVENT half was covered by #30456), but when neither the event
nor the cache knows the workspace, both download helpers silently fell
back to the PRIMARY workspace token — Slack then returns an HTML login
page instead of file bytes for any non-primary workspace file.
Slack private file URLs embed the owning workspace id
(files-pri/<TEAM_ID>-<FILE_ID>/...), so _resolve_download_token now
prefers: explicit team_id -> URL-embedded team id -> primary token.
Both _download_slack_file and _download_slack_file_bytes route through
it.
Deferred from #59742 (out of this correctness cluster's scope): the
channel→team disk persistence, the pre-send conversations.info probe
loop, and the thread-file ingestion feature.
Reapplied from #59742 by @benjamin2026-dot onto the current adapter
(original targeted the pre-#30456 download sites).
benjamin2026-dot
ca8aee87e8