Expose templates.default — a starter flake that consumes OmniXY as an
input (dependency model): omnixy.lib.mkSystem + nixosModules.omnixy +
a placeholder host. Lets adopters track OmniXY with `nix flake update`
instead of forking. See templates/default/README.md.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>