refactor(nix): order let bindings

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

@@ -7,7 +7,6 @@
 # Nord theming for the graphical layer, driven from one base16 scheme by Stylix.
 let
   cfg = config.modules.desktop.utilities.theming; # NOLINT(let_order)
-  user = config.user.name;
 
   # 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.
@@ -16,6 +15,7 @@ let
       -size 2560x1440 gradient:'#2E3440'-'#3B4252' \
       "$out"
   '';
+  user = config.user.name;
 in
 {
   options.modules.desktop.utilities.theming.enable =