PXE Server

Flake exports squashfs of 2 configurations:

• squashfsStore - Full KDE based desktop configuration.nix
• squashfsStoreMin - Console only (faster to build) configuration-min.nix

Using NixOS 25.05 because NFS mount in stage 1 is broken for unknown reasons in subsequent releases.

Also exports pixiecoreServer which hosts a PXE boot menu allowing one to select an OS (or boot the local drive).