Add a dedicated user option for windows

lib/modules/windows.nix

@@ -1,4 +1,4 @@
-{ lib, config, ... }:
+{ lib, config, options, ... }:
   let
     inherit (lib)
       mkOption
@@ -7,7 +7,16 @@
       types
     ;
 
-    setupUser = lib.strings.stringToCharacters config.valhalla.setupUser.name;
+    users = config.valhalla.users;
+    setupUser = config.valhalla.setupUser.name;
+
+    capitalize = text:
+      let
+        chars = lib.strings.stringToCharacters text;
+      in lib.strings.concatStrings (
+        [(lib.strings.toUpper (builtins.elemAt chars 0))] ++
+        (lib.lists.drop 1 chars)
+      );
 
     winType = types.submodule (
       { config, ... }: {
@@ -15,10 +24,16 @@
           setupUser = mkOption {
             type = types.str;
             description = "The name of the user for setting up Windows.";
-            default = lib.strings.concatStrings (
+            default = capitalize setupUser;
-              [(lib.strings.toUpper (builtins.elemAt setupUser 0))] ++
+          };
-              (lib.lists.drop 1 setupUser)
+
-            );
+          users = mkOption {
+            type = options.valhalla.users.type;
+            description = "The users to add.";
+            default = lib.attrsets.concatMapAttrs (
+              name: options: {
+                ${capitalize name} = options;
+              }) users;
           };
 
           dualboot = {