Stylix does not theme Noctalia shell or its greeter

On NixOS with Stylix, changing base16Scheme does not recolor the Noctalia desktop shell. Noctalia uses its own builtin theme name in ~/.config/noctalia/conf.d/theme.toml ([theme] source="builtin", builtin="Gruvbox", mode="dark"), and noctalia-greeter has a separate appearance scheme/theme_mode in its settings TOML that is copied through the Nix store, so it needs a rebuild. Bar widget colors use semantic role names (on_surface, primary, magenta) and follow whichever scheme is active. For a one-switch theme, define one Nix option that maps to Stylix scheme file + Noctalia builtin name + editor colorscheme, and generate both Noctalia TOMLs from it.