scripts: fix create-host flake.nix insertion point

Fix bug where new hosts were added outside of nixosConfigurations block
instead of inside it.

Issues fixed:
1. Pattern was looking for "packages =" but actual text is "packages = forAllSystems"
2. Replacement was putting new entry AFTER closing brace instead of BEFORE
3. testvm01 was at top-level flake output instead of in nixosConfigurations

Changes:
- Update pattern to match "packages = forAllSystems"
- Put new entry BEFORE the closing brace of nixosConfigurations
- Move testvm01 to correct location inside nixosConfigurations block

Result: nix flake show now correctly shows testvm01 as NixOS configuration

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 }}";