Refactor the Nix config management.

nix-system-configs/modules/local/hostname_username.nix

@@ -0,0 +1,26 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}: {
+  # Example host-specific module: set hostname and small per-host packages
+  # The machine file can set `config.local.hostname` before importing this module if desired.
+  networking.hostName = config.local.hostname or "default-hostname";
+
+  # Expose a small list that machine files can use as hostPackages
+  myLocal.hostname.packages = with pkgs; [];
+
+  users.users.${config.local.username or "defaultuser"} = {
+    isNormalUser = true;
+    description = config.local.userDescription or "NixOS Playground";
+    extraGroups = ["networkmanager" "wheel" "seat" "acme"];
+    packages = with pkgs; [];
+    initialPassword = "nixos"; # Simple, change on first login
+
+    # NitroKey3C OpenGPG /w pin - Christine's key, for alpha run only, later to be replaced with the more official key
+    openssh.authorizedKeys.keys = [
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIO3pjIXlpg7H9h1RrmdxbIRnDIdQvf/EZKI9PG2/rY7D openpgp:0x8BCD4992"
+    ];
+  };
+}