Style the publish stepper; drop its "Keep editing" cancel button
The publish flow's confirm step had an unstyled publication <select> and an
unstyled publish button, plus a "Keep editing" cancel. Remove the cancel
button (onCancel stays for the inline create-publication step), and style the
picker + primary action to match the editor's .publish__select / .publish__button
(token border, sun fill), with the working-status text muted.