feat: Add templates for external configs

templates/system/default.nix

@@ -0,0 +1,56 @@
+{ inputs, ... }:
+
+# ============================================================================
+# External System Module Template
+# ============================================================================
+# This is a template for creating external system configuration modules
+# that can be referenced from nixos-systems/inventory.nix using builtins.fetchGit
+#
+# Usage in inventory.nix:
+#   "my-type" = {
+#     devices = {
+#       "hostname" = builtins.fetchGit {
+#         url = "https://github.com/your-org/your-config-repo";
+#         rev = "commit-hash";
+#       };
+#     };
+#   };
+#
+# This module will receive the same `inputs` flake inputs as the main
+# nixos-systems configuration, allowing you to use nixpkgs, home-manager, etc.
+
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+{
+  # ========== Module Options ==========
+  # Define any custom options your module needs
+  options = {
+    # Example: myorg.customOption = lib.mkOption { ... };
+  };
+
+  # ========== Module Configuration ==========
+  config = {
+    # Your system configuration goes here
+    # This can include any NixOS options
+
+    # Example: Set timezone
+    # time.timeZone = "America/New_York";
+
+    # Example: Install packages
+    # environment.systemPackages = with pkgs; [
+    #   vim
+    #   git
+    # ];
+
+    # Example: Configure services
+    # services.openssh.enable = true;
+
+    # Example: Use ugaif options if available from nixos-systems
+    # ugaif.users.myuser.enable = true;
+  };
+}