Restructure to focus on nix.

common/users/admin.nix

@@ -0,0 +1,34 @@
+{
+  config,
+  lib,
+  foelib,
+  ...
+}: let
+  inherit (lib) mkIf mkOption mkEnableOption optionals types;
+  cfg = config.foehammer.users.admin;
+in {
+  options.foehammer.users.admin = {
+    enable = mkEnableOption "Enable a wheel admin user.";
+    hashedPasswordFile = mkOption {
+      type = with types; nullOr str;
+      default = null;
+    };
+  };
+  config = mkIf cfg.enable {
+    users.users.admin = {
+      createHome = true;
+      description = "SSH Admin User.";
+      group = "admin";
+
+      extraGroups = ["wheel"] ++ optionals config.virtualisation.docker.enable ["docker"];
+      isNormalUser = true;
+      uid = 9999;
+
+      openssh.authorizedKeys.keys = foelib.getSSHKeys "foehammer";
+
+      hashedPasswordFile = cfg.hashedPasswordFile;
+    };
+
+    users.groups.admin.gid = config.users.users.admin.uid;
+  };
+}