feat(hostSpec): add module to define hosts in flake

modules/hostSpec/default.nix

@@ -0,0 +1,29 @@
+{
+  lib,
+  config,
+  inputs,
+  ...
+}:
+let
+  inherit (builtins) mapAttrs;
+  inherit (lib) mkOption;
+  inherit (lib.types) lazyAttrsOf submodule;
+  cfg = config.hostSpec;
+  hostOptions = submodule { };
+  mkSystem =
+    hostName: _hostConfig:
+    inputs.nixpkgs.lib.nixosSystem {
+      system = "x86_64-linux";
+      modules = [ { networking = { inherit hostName; }; } ];
+    };
+in
+{
+  options.hostSpec.hosts = mkOption {
+    type = lazyAttrsOf hostOptions;
+    default = { };
+  };
+
+  config = {
+    flake.nixosConfigurations = mapAttrs mkSystem cfg.hosts;
+  };
+}