proxmox: add VM automation with OpenTofu and Ansible

Add automated workflow for building and deploying NixOS VMs on Proxmox including template2 host configuration, Ansible playbook for image building/deployment, and OpenTofu configuration for VM provisioning with cloud-init.

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

hosts/template2/scripts.nix

@@ -0,0 +1,33 @@
+{ pkgs, ... }:
+let
+  prepare-host-script = pkgs.writeShellScriptBin "prepare-host.sh"
+    ''
+      echo "Removing machine-id"
+      rm -f /etc/machine-id || true
+
+      echo "Removing SSH host keys"
+      rm -f /etc/ssh/ssh_host_* || true
+
+      echo "Restarting SSH"
+      systemctl restart sshd
+
+      echo "Removing temporary files"
+      rm -rf /tmp/* || true
+
+      echo "Removing logs"
+      journalctl --rotate || true
+      journalctl --vacuum-time=1s || true
+
+      echo "Removing cache"
+      rm -rf /var/cache/* || true
+
+      echo "Generate age key"
+      rm -rf /var/lib/sops-nix || true
+      mkdir -p /var/lib/sops-nix
+      ${pkgs.age}/bin/age-keygen -o /var/lib/sops-nix/key.txt
+    '';
+in
+{
+  environment.systemPackages = [ prepare-host-script ];
+  users.motd = "Prepare host by running 'prepare-host.sh'.";
+}