feat: defines machine-specific variables

hosts/dandelion/variables.nix

@@ -0,0 +1,17 @@
+{
+  lib,
+  config,
+  ...
+}: let
+  inherit (lib) mkOption types;
+  inherit (config.liv) variables;
+in {
+  options.liv.variables.dandelion = {
+    thisMachine = mkOption {
+      default = "dandelion.srv.${variables.primaryDomain}";
+      type = types.str;
+      readOnly = true;
+      description = "Domain of this specific machine";
+    };
+  };
+}