Config now supports named contexts (like kubectl), each bundling
domain, kube-context, ssh-host, infra-dir, and acme-email. Legacy
flat config auto-migrates to a "production" context on load.
- sunbeam config set --domain sunbeam.pt --host user@server
- sunbeam config use-context production
- sunbeam config get (shows all contexts)
Auth tokens stored per-domain (~/.local/share/sunbeam/auth/{domain}.json)
so local and production don't clobber each other. pm and auth commands
read domain from active context instead of K8s cluster discovery.