ns2: migrate to OpenTofu management

- Remove hosts/template/ (legacy template1) and give each legacy host
  its own hardware-configuration.nix copy
- Recreate ns2 using create-host with template2 base
- Add secondary DNS services (NSD + Unbound resolver)
- Configure Vault policy for shared DNS secrets
- Fix create-host IP uniqueness validator to check CIDR notation
  (prevents false positives from DNS resolver entries)

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

hosts/ns2/configuration.nix

@@ -7,23 +7,38 @@
 
 {
   imports = [
-    ../template/hardware-configuration.nix
+    ../template2/hardware-configuration.nix
 
     ../../system
+    ../../common/vm
+
+    # DNS services
     ../../services/ns/secondary-authorative.nix
     ../../services/ns/resolver.nix
-    ../../common/vm
   ];
 
+  # Host metadata
+  homelab.host = {
+    tier = "prod";
+    role = "dns";
+    labels.dns_role = "secondary";
+  };
+
+  # Enable Vault integration
+  vault.enable = true;
+
+  # Enable remote deployment via NATS
+  homelab.deploy.enable = true;
+
   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 = "ns2";
   networking.domain = "home.2rjus.net";
   networking.useNetworkd = true;
   networking.useDHCP = false;
+  # Disable resolved - conflicts with Unbound resolver
   services.resolved.enable = false;
   networking.nameservers = [
     "10.69.13.5"
@@ -47,14 +62,7 @@
     "nix-command"
     "flakes"
   ];
-  vault.enable = true;
-  homelab.deploy.enable = true;
-
-  homelab.host = {
-    role = "dns";
-    labels.dns_role = "secondary";
-  };
-
+  nix.settings.tarball-ttl = 0;
   environment.systemPackages = with pkgs; [
     vim
     wget
@@ -67,5 +75,5 @@
   # Or disable the firewall altogether.
   networking.firewall.enable = false;
 
-  system.stateVersion = "23.11"; # Did you read the comment?
-}
+  system.stateVersion = "25.11"; # Did you read the comment?
+}