Appearance: remove dead profile_name/bio write + Prutter toggle only in Hub
(1) The save handler wrote profile_name/profile_bio which are not in the
form → every save set them to null (could wipe the federation actor name).
Removed from the UPDATE; they remain fallback-driven (title/description).
(2) Prutter toggle is now Hub-only + premium, so only show it in Hub mode
instead of on every (including solo) site where it 404s anyway.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@…>