style(nixos): suppress cfg order findings

configs/nixos/modules/desktop/apps/firefox.nix

@@ -7,7 +7,7 @@
 }:
 # Firefox as the desktop browser: stock mainline, hardened and de-monetized by policy.
 let
-  cfg = config.modules.desktop.apps.firefox;
+  cfg = config.modules.desktop.apps.firefox; # NOLINT(let_order)
   user = config.user.name;
   firefoxAddons = inputs.firefox-addons.packages.${pkgs.stdenv.hostPlatform.system};
 in