docs(ingress): describe the claim handoff only

A guide that documents flags the release does not have is a defect, so the
ingress guide, the command reference, the feature map and the configuration page
now describe the one handoff: the claim code, the hidden-input fill in the
human's own terminal, `psamvault pending` and `--cancel`, and the limits that
come with it. The guide states plainly what is deferred instead of implying it
exists.
