remove "parts" directory and restructure modules

modules/user-rpqt.nix

@@ -0,0 +1,21 @@
+{ lib, pkgs, ... }:
+{
+  users.users.rpqt = {
+    isNormalUser = true;
+
+    createHome = lib.mkDefault true;
+    home = lib.mkDefault "/home/rpqt";
+
+    description = "Romain Paquet";
+
+    shell = pkgs.zsh;
+
+    openssh.authorizedKeys.keys = [
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIGa8R8obgptefcp27Cdp9bc2fiyc9x0oTfMsTPFp2ktE rpqt@haze"
+    ];
+
+    extraGroups = [ "wheel" ];
+  };
+
+  programs.zsh.enable = true;
+}