nixos/release: add Plasma 6 ISO variant

nixos/modules/installer/cd-dvd/installation-cd-graphical-calamares-plasma6.nix

@@ -0,0 +1,46 @@
+# This module defines a NixOS installation CD that contains Plasma 6.
+
+{ pkgs, ... }:
+
+{
+  imports = [ ./installation-cd-graphical-calamares.nix ];
+
+  isoImage.edition = "plasma6";
+
+  services.xserver = {
+    desktopManager.plasma6.enable = true;
+
+    # Automatically login as nixos.
+    displayManager = {
+      sddm.enable = true;
+      autoLogin = {
+        enable = true;
+        user = "nixos";
+      };
+    };
+  };
+
+  environment.systemPackages = [
+    # FIXME: using Qt5 builds of Maliit as upstream has not ported to Qt6 yet
+    pkgs.maliit-framework
+    pkgs.maliit-keyboard
+  ];
+
+  system.activationScripts.installerDesktop = let
+
+    # Comes from documentation.nix when xserver and nixos.enable are true.
+    manualDesktopFile = "/run/current-system/sw/share/applications/nixos-manual.desktop";
+
+    homeDir = "/home/nixos/";
+    desktopDir = homeDir + "Desktop/";
+
+  in ''
+    mkdir -p ${desktopDir}
+    chown nixos ${homeDir} ${desktopDir}
+
+    ln -sfT ${manualDesktopFile} ${desktopDir + "nixos-manual.desktop"}
+    ln -sfT ${pkgs.gparted}/share/applications/gparted.desktop ${desktopDir + "gparted.desktop"}
+    ln -sfT ${pkgs.calamares-nixos}/share/applications/io.calamares.calamares.desktop ${desktopDir + "io.calamares.calamares.desktop"}
+  '';
+
+}

nixos/release.nix

@@ -177,6 +177,12 @@ in rec {
     inherit system;
   });
 
+  iso_plasma6 = forMatchingSystems supportedSystems (system: makeIso {
+    module = ./modules/installer/cd-dvd/installation-cd-graphical-calamares-plasma6.nix;
+    type = "plasma6";
+    inherit system;
+  });
+
   iso_gnome = forMatchingSystems supportedSystems (system: makeIso {
     module = ./modules/installer/cd-dvd/installation-cd-graphical-calamares-gnome.nix;
     type = "gnome";