refactor(nixos): inline module enable conditions

configs/nixos/modules/desktop/utilities/theming.nix

@@ -6,7 +6,6 @@
 }:
 # Nord theming for the graphical layer, driven from one base16 scheme by Stylix.
 let
-  cfg = config.modules.desktop.utilities.theming; # NOLINT(let_order)
 
   # A single static Nord wallpaper, drawn as a vertical gradient across the
   # Polar Night shades so it needs no committed binary and no network fetch.
@@ -21,7 +20,7 @@ in
   options.modules.desktop.utilities.theming.enable =
     lib.mkEnableOption "Nord theming of the graphical layer via Stylix";
 
-  config = lib.mkIf cfg.enable {
+  config = lib.mkIf config.modules.desktop.utilities.theming.enable {
     stylix = {
       enable = true;