feat: add themes derivation

flake.nix

@@ -46,6 +46,14 @@
               cp -r ./* $out/
             '';
           };
+        packages.themes = pkgs.stdenv.mkDerivation {
+          name = "themes";
+          phases = [ "installPhase" ];
+          installPhase = ''
+            mkdir -p $out
+            cp ${helix}/runtime/themes/*.toml $out/
+          '';
+        };
         packages.karnaugh = pkgs.rustPlatform.buildRustPackage (final: {
           pname = "karnaugh";
           version = "0.1.5";