jovian-install-iso: init

OLED users can't get network on the default installer, so build our own,
slightly Deck flavored one.

overlay.nix

@@ -93,4 +93,6 @@ rec {
 
   decky-loader = final.callPackage ./pkgs/decky-loader/stable.nix { };
   decky-loader-prerelease = final.callPackage ./pkgs/decky-loader/prerelease.nix { };
+
+  jovian-install-iso = (final.nixos ./support/install-iso/configuration.nix).config.system.build.isoImage;
 }

support/install-iso/configuration.nix

@@ -0,0 +1,31 @@
+{ lib, modulesPath, pkgs, ... }:
+
+{
+  imports = [
+    # we don't want to pull in Calamares, as it's not Jovian-aware
+    (modulesPath + "/installer/cd-dvd/installation-cd-graphical-base.nix")
+    ../../modules
+  ];
+
+  config = {
+    services.desktopManager.plasma6.enable = true;
+
+    # Automatically login as nixos.
+    services.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
+    ];
+
+    jovian.devices.steamdeck.enable = true;
+    hardware.pulseaudio.enable = lib.mkForce false;
+  };
+}