Service names are used for service discovery via the embedded DNS server: <service-name>.internal (implemented in #16)
A service name must be a valid DNS subdomain. See DNS Subdomain Names in k8s docs: https://kubernetes.io/docs/concepts/overview/working-with-objects/names/#dns-subdomain-names

The validation can be implemented in ServiceSpec.Validate which should automatically apply it to both individual service and Compose deployments.