v89 added the 'bot' role for the Matrix email-review bot's endpoints but kept it
out of the UI, leaving no click-path to assign it. Add 'bot' to the Settings ->
Admin edit-user role dropdown (the teammate-invite form stays member/admin only —
provisioning an agent account is an admin re-classification of a dedicated user,
not a teammate invite). The backend update validator already accepts 'bot'.
Frontend-only, no schema change.