GiteaClient defaulted to cfg.services.git (http://git:3000), which only
resolves inside the compose network. The host-side bib-refresh-iom
timer's IOM alert step died on it every night (and before Nov 11 it was
also writing a worktree's bib). Use GITEA_API_URL when set, the
internal service when its name resolves, else https://git.<domain>.