Add basic plasma module

nixos/modules/des/plasma/default.nix

@@ -0,0 +1,32 @@
+{ config, lib, pkgs, ... }:
+
+{
+  services.xserver = {
+    enable = true;
+
+    displayManager.sddm = {
+      enable = true;
+      # https://discourse.nixos.org/t/plasma-wayland-session-not-available-from-sddm/13447/2
+      settings.Wayland.SessionDir = "${pkgs.plasma5Packages.plasma-workspace}/share/wayland-sessions";
+    };
+    
+    desktopManager.plasma5 = {
+      enable = true;
+      useQtScaling = true;
+
+      excludePackages = with pkgs.libsForQt5; [
+        elisa
+        okular
+        khelpcenter
+        konsole
+        print-manager
+        plasma-systemmonitor
+        gwenview
+      ];
+    };
+    
+    excludePackages = with pkgs; [
+      xterm
+    ];
+  };
+}