Add a 'Get CCS Bar' promo banner + card to the dashboard (mirroring the
OpenRouter promo pattern + design system) so users discover the macOS menu-bar
app, with a macOS-aware install CTA. Add a user-facing docs/ccs-bar.md covering
what it is, install via 'ccs bar install', launch, what it shows, uninstall,
and the loopback requirement -- closing the docs-sync gap for the new ccs bar
command.