add host to service-status output

[willkg]

Service status prints something like this:

stage
=====

  tecken        version       709cb61b0dcdb61f8d344cae27dd0c68db17a6f3 main
                status        identical


prod
====

  tecken        version       709cb61b0dcdb61f8d344cae27dd0c68db17a6f3 main
                status        identical

We just did a cutover so I don't know whether stage points to the old stage or the new stage without additionally checking pyproject.toml. It'd be great to know what the stage and prod hosts were.