fixup! scripts: fix boot device and hardware-configuration import

Update create-host template to match template2 configuration:
- Change boot device from /dev/sda to /dev/vda (correct for Proxmox VMs)
- Import ../template2/hardware-configuration.nix instead of ../template
- Remove obsolete comment about systemd-boot

This fixes bootstrap failures where GRUB couldn't install to /dev/sda
and filesystem labels didn't match.

All VMs cloned from template2 share the same hardware config, so
importing the shared file avoids duplication.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

scripts/create-host/templates/configuration.nix.j2

@@ -7,16 +7,15 @@
 
 {
   imports = [
-    ../template/hardware-configuration.nix
+    ../template2/hardware-configuration.nix
 
     ../../system
     ../../common/vm
   ];
 
   nixpkgs.config.allowUnfree = true;
-  # Use the systemd-boot EFI boot loader.
   boot.loader.grub.enable = true;
-  boot.loader.grub.device = "/dev/sda";
+  boot.loader.grub.device = "/dev/vda";
 
   networking.hostName = "{{ hostname }}";
   networking.domain = "{{ domain }}";