Refactor modules into nixos and home-manager

modules/nixos/system/desktop/kde.nix

@@ -0,0 +1,37 @@
+{ config, lib, pkgs, ... }:
+
+let cfg = config.modules.system.desktop.kde;
+in {
+  options.modules.system.desktop.kde = {
+    enable = lib.mkOption {
+      default = false;
+      example = true;
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    services = {
+      xserver = {
+        enable = true;
+      };
+      desktopManager.plasma6.enable = true;
+      displayManager.sddm = {
+        enable = true;
+        wayland.enable = true;
+      };
+    };
+
+    networking.networkmanager.enable = true;
+
+    user.packages = with pkgs; [
+      kmail
+      mpv
+    ];
+
+    environment.systemPackages = with pkgs; [
+      adw-gtk3
+    ];
+
+    home.services.gpg-agent.pinentryPackage = pkgs.pinentry-qt;
+  };
+}