docker_host auto-mount did not expose the socket on runner 6.3.1; mount it
explicitly so the deploy.json step's docker exec works.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Set container.docker_host to "" (auto-detect) instead of "-" so workflow
steps can reach the docker daemon - fixes the "Update deploy.json" step
that does `docker exec xetup-web`.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>