Keep WindowOpacityButton in sync with Settings so 96–99% stays
selectable from the top-tabs control as well.
Co-authored-by: Cursor <cursoragent@cursor.com>
Expose whole-window transparency via setOpacity with settings and a top-bar quick control, persisting across restarts and syncing across windows.
Co-authored-by: Cursor <cursoragent@cursor.com>