nixos-26.05 removed lix_2_93, which the lix-module release-2.93 branch
hard-pins via lixFromNixpkgs (no 2.94 module release exists yet). Drop
the lix-module input and set nix.package = pkgs.lix, which is Lix 2.94.2
on 26.05 — so we stay on Lix, just sourced from nixpkgs.
Also: newer disko dropped the btrfs `label` option; pass -L nixos via
extraArgs instead so the impermanence rollback still finds the "nixos"
label.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
nixos-25.11 reached end-of-life (frozen upstream at b6018f8), so
`nix flake update` no longer pulls system package updates. Move the
default nixpkgs channel to the current stable release, nixos-26.05.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
