Gitea's Debian registry is immutable, so re-uploading an existing version returns
409. With --fail that aborted the release on any re-run / repeat push at the same
version. Now we capture the HTTP code: 2xx = uploaded, 409 = already published
(skip), anything else = fail with the body. Also fixed the stale skip message
(REGISTRY_TOKEN, not PACKAGES_TOKEN).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
jessey
