Api Admin Disable Host

Admin-initiated disable of a host (potentially owned by another user).

Unlike kick (which is a one-shot connection drop), disable is persistent: the host stays rejected at handshake until someone re-enables it.

The reason field on the disabled meta is prefixed with "[admin: <email>]" so the owner sees in their own dashboard that the action was administrative, not their own.

Reason for not accepting a free-text reason from the admin here: the admin panel is the operator's tool, and we keep its actions terse. If audit detail is needed, it lives in the structured logs (admin_email + target).