From the server the public URL goes through ArvanCloud and returned 504/000 (2026-10-07), so the
final health step failed even for a healthy service. It now asks the gunicorn socket (path read from
the unit) with our Host header first. DEPLOY_BUNDLE=<file> fetches from a git bundle instead of Gitea,
only when set explicitly; without it an unreachable Gitea still stops the deploy.
Tested: probe_health against a throwaway unix-socket server and a dead URL (bash -n clean).
Not tested: the whole script end to end, until the next deploy.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>