Refactor the whole configuration

Reviewed-on: #1

modules/nixos/multimedia/art/default.nix

@@ -0,0 +1,15 @@
+{ pkgs, username, ... }:
+
+{
+  environment.persistence."/nix/persist" = {
+    users."${username}".directories = [
+      ".local/share/krita"
+      ".config/GIMP"
+    ];
+  };
+  
+  environment.systemPackages = with pkgs; [
+    krita
+    gimp
+  ];
+}