bos-settings was scaffolded but never compiled. Fixes:
- main.rs: import gtk4::prelude (connect_activate/run)
- window.rs: disambiguate WidgetExt::display(); drop unused GBox import
- hyprland.rs: Label has no set_monospace -> use the monospace CSS class
- theme.rs: drop unused prelude import
Also switch package.yml to secrets.REGISTRY_TOKEN (scoped write:package),
since the auto Actions token is not authorized for the owner registry.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>