Merge add-nixica-implementation into master for 0.2.0 release
Brings the flake check fix (MR !4) into master so we can retag 0.2.0.
Included changes
- Remove flake-parts.flakeModules.flakeModules from modular.nix — fixes nix flake check for consumer projects
- Re-export flakeModules via nixica.flakeModules.flakeModules for module-provider projects
- Add regression test it-passes-flake-check