manage_etc_hosts: true rewrites /etc/hosts on every VM boot, removing
the manually-added gitea entry. This broke image pulls after bare_srv_1
reboot because containerd couldn't resolve the Gitea auth token URL.
Changes:
- Add bootcmd to ensure 10.10.10.1 gitea in /etc/hosts on every boot
- Add containerd registry mirror config in write_files (was only in bootstrap)
- Add registry config_path to containerd config.toml
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>