🐛 [shared] Fix missing background on sddm

shared/desktop/modules/sddm.nix

@@ -1,4 +1,9 @@
-{ pkgs, theme, ... }:
+{
+  pkgs,
+  lib,
+  theme,
+  ...
+}:
 let
   flavor = theme.flavor;
 in
@@ -8,7 +13,7 @@ in
       flavor = flavor;
       font = theme.nerdFont;
       fontSize = "9";
-      background = builtins.toString ../assets/catppuccin_high.png;
+      background = builtins.toString (lib.custom.relativeToRoot "shared/assets/catppuccin_high.png");
       loginBackground = true;
     })
   ];