refactor: use nixpkgs.system config option

config/config.nix

@@ -18,6 +18,8 @@ in
     experimental-features = nix-command flakes ca-derivations
     restrict-eval = false
   '';
+
+  nixpkgs.system = if isMobile then "aarch64-linux" else "x86_64-linux";
   nixpkgs.config.allowUnfree = true;
 
   # Use the systemd-boot EFI boot loader.

flake.nix

@@ -35,7 +35,6 @@ outputs = { self,
 
     mkConfig =
       { machine,
-        system ? "x86_64-linux",
         configModules ? [ ./config ],
         configExtraModules ? [],
         homeModules ? [ ./home-manager ],
@@ -43,7 +42,6 @@ outputs = { self,
       }:
       {
         "toki-${machine}" = nixpkgs.lib.nixosSystem {
-          inherit system;
           modules =
             configModules ++
             configExtraModules ++
@@ -79,7 +77,6 @@ outputs = { self,
       } //
       mkConfig {
         machine = "air";
-        system = "aarch64-linux";
         configExtraModules = [
           ./mobile/config.nix
           (import (mobile-nixos + /lib/configuration.nix)