Refactor the Nix config management.

nix-system-configs/modules/bootloader/seabios.nix

@@ -0,0 +1,29 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}: {
+  # SeaBIOS / legacy BIOS bootloader settings for VMs
+  boot.loader.grub.enable = lib.mkForce true;
+  boot.loader.grub.device = "/dev/vda";
+  boot.loader.grub.efiSupport = lib.mkForce false;
+
+  # Bootloader - GRUB for Legacy BIOS
+  boot.loader.systemd-boot.enable = lib.mkForce false;
+  boot.loader.grub = {
+    enable = true;
+    device = "/dev/vda"; # Install GRUB to the disk
+    efiSupport = false; # Disable UEFI
+  };
+  boot.initrd.availableKernelModules = ["virtio_pci" "virtio_scsi" "ahci" "sd_mod" "virtio_blk"];
+
+  fileSystems."/" = {
+    device = "/dev/vda1";
+    fsType = "ext4"; # Use "btrfs" or "xfs" if you formatted it differently
+  };
+
+  virtualisation.qemu.enable = true;
+
+  myBoot.seabiosPackages = with pkgs; [];
+}