migrate configuration.nix into flexible modular flake setup

modules/users.nix

@@ -0,0 +1,14 @@
+{ config, pkgs, ... }:
+
+{
+  # Define the main user account
+  users = {
+    users.schulze = {
+      isNormalUser = true;
+      description = "Felix Schulze";
+      extraGroups = [ "networkmanager" "wheel" "docker" ];
+      shell = pkgs.fish;
+    };
+    groups.libvirtd.members = ["schulze"];
+  };
+}