Authorize the WSL workstation as a nix-cache remote-builder client

Adds debian@surface's existing SSH key (already used as its admin
key elsewhere in this repo) to vars.remoteBuilderAuthorizedKeys so
nix-cache will accept it as a distributed-build client once deployed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01La55Nsss8jZ7ZuzUV9mfot

modules/build-types/pxe-boot.nix

@@ -76,9 +76,7 @@ let
     choose target && goto ''${target}
 
     :nixos
-    kernel ''${base}/nixos/bzImage ip=dhcp
-    initrd ''${base}/nixos/initrd
-    boot
+    chain ''${base}/nixos/netboot.ipxe
 
     :rescue
     chain ''${base}/systemrescue.ipxe
@@ -91,6 +89,10 @@ let
   '';
 in
 {
+  imports = [
+    ../pxe-boot/stage-installer-artifacts.nix
+  ];
+
   environment.systemPackages = with pkgs; [
     ipxe
   ];