feat(configurations): add darwin config support

nix/configurations.nix

@@ -6,6 +6,7 @@
 }:
 let
   inherit (lib) nixosSystem;
+  inherit (inputs.nix-darwin.lib) darwinSystem;
   inherit (lib.lists) optional;
   inherit (lib.attrsets) mapAttrs;
   inherit (cfg.lib.modules) forAllUsers';
@@ -35,6 +36,10 @@ let
             (value.extraCfg or { })
           ] ++ optional value.graphical cfg.modules.nixos.graphical;
         }
+      else if class == "darwin" then
+        darwinSystem {
+          modules = [ cfg.modules.darwin.default ];
+        }
       else
         { }
     ) hosts;
@@ -42,4 +47,5 @@ in
 {
   imports = [ inputs.home-manager.flakeModules.home-manager ];
   flake.nixosConfigurations = mkConfigurations "nixos" hosts.nixos;
+  flake.darwinConfigurations = mkConfigurations "darwin" hosts.darwin;
 }

nix/manifest.nix

@@ -7,6 +7,7 @@
       shell = "fish";
       pubkey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAILdsZyY3gu8IGB8MzMnLdh+ClDxQQ2RYG9rkeetIKq8n rafiq";
     };
+    hosts.darwin.venus = { };
     hosts.nixos = {
       nemesis = {
         graphical = true;

nix/meta.nix

@@ -74,9 +74,12 @@ in
             type = lazyAttrsOf userOpts;
             default = { };
           };
-          hosts = mkOption {
-            # hosts.nixos, hosts.darwin, etc.
-            type = lazyAttrsOf (lazyAttrsOf hostOpts);
+          hosts.nixos = mkOption {
+            type = lazyAttrsOf hostOpts;
+            default = { };
+          };
+          hosts.darwin = mkOption {
+            type = lazyAttrsOf raw;
             default = { };
           };
         };

nix/modules/machine/platform.nix

@@ -11,4 +11,5 @@
       boot.kernelModules = [ "kvm-${platform}" ];
       nixpkgs.hostPlatform = "${arch}-linux";
     };
+  flake.modules.darwin.default.nixpkgs.hostPlatform = "x86_64-darwin";
 }