The last of the inline two-step deletes, and the one with the most reach: a
key delete revokes it from every server at once, and for a generated key the
stored private half goes with it. That copy is the only one Vantage holds, so
unlike an uploaded key this cannot be undone by pasting the public half back.
Body names how many servers lose access, and says the private key is destroyed
only when there is one to destroy.
The delete error moves out of the toast and into the dialog, which stays open
on failure, matching the server and monitor deletes.