Migrate old home-manager modules

modules/home-manager/colors.nix

@@ -0,0 +1,15 @@
+{
+  lib,
+  ...
+}:
+let
+  inherit (lib) types mkOption;
+in
+{
+  options.colorscheme = {
+    name = mkOption {
+      type = types.str;
+      default = "catppuccin-mocha";
+    };
+  };
+}