These optional-asset uploads are non-fatal, but failures were warn-only — the
user got a silently-missing thumbnail or torrent with no signal. Both upload
services now emit a 'warning' status at the point of failure and append a note
to the final 'Published' status (downgraded to warning variant) listing what
failed. Cloudflare-upload audit #5.
Test: tests/services/s3-upload-optional-asset-failures.test.mjs.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
