A test that reads every manifest in a catalogue checkout and parses it with the
control plane's own parser, rather than asserting against a fixture: whether the
manifests as written are accepted is the question, and a copy of one proves nothing
about the other seventy-one.
Skipped unless MESH_CATALOGUE names a checkout, so it costs nothing in ordinary
runs and is there when the catalogue changes shape. It also refuses to pass if no
endpoint is named, because a run that validated nothing would otherwise read as
success.
