The Clear Plate button (and 4 other features on the Printers page) read
their state from /settings, which requires SETTINGS_READ. Granting that
permission also adds the Settings nav item and leaks SMTP/LDAP/MQTT
credentials — exactly what users were trying to avoid by giving an
operator only printers:clear_plate.
New /settings/ui-preferences endpoint returns a curated, opt-in subset
of non-sensitive fields. Matches the existing /default-sidebar-order
precedent. PrintersPage switched to the new endpoint; admin pages still
use /settings for full access.