Add local/remote classes to the group header buttons and introduce a
--group-accent CSS variable used with color-mix for background, text tint,
hover state, and an inset accent shadow. Local headers use --color-info and
remote headers use --color-accent.
This is a visual-only change (no toggle/behavior changes): group headers now
have a subtle, distinct accent for local vs. remote sections instead of a
uniform muted surface.
Christoph
216b552e61