Extend stopped-container protection to an explicit lease contract
(org.oblachno.lease-until / org.oblachno.owner) honored by every cleanup
path. Consolidate the duplicated inline prune logic from docker-prune
and the healthcheck into a single tiered runner-cleanup.sh; remove the
unfiltered `system prune -af --volumes` / `volume prune` paths that could
wipe a job's volumes mid-run, and keep warm base images under pressure.
At critical disk usage the healthcheck now stops admitting new work
(stops gitea-runner.service once no CI job is in flight) and resumes it
automatically after recovery. The runner config declares capacity, and
the role refuses to install on production-marked hosts.
Emil Simeonov
kireto