sonarr was the only *arr service without its systemd unit in the repo —
it was treated as package-managed and never captured, so a london-b
rebuild would lose the unit. Capture the running unit (APT/mono Sonarr
v3) into ansible/services/sonarr/sonarr.service and have the media_stack
role deploy it to /etc/systemd/system like radarr/lidarr/prowlarr,
overriding the package-owned copy. Move sonarr out of the
package-managed enable loop into the custom-unit deploy + enable loops.
