redid theming system to utilize stylix, purging unused module files next

modules/nvim/default.nix

@@ -3,7 +3,6 @@
 {
   programs.nixvim = {
     enable = true;
-    colorschemes.nord.enable = true;
     plugins.nvim-tree.enable = true;
     plugins.treesitter.enable = true;
     plugins.lualine.enable = true;