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>

terraform/README.md

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+# OpenTofu Configuration for Proxmox
+
+This directory contains OpenTofu configuration for managing Proxmox VMs.
+
+## Setup
+
+1. **Create a Proxmox API token:**
+   - Log into Proxmox web UI
+   - Go to Datacenter → Permissions → API Tokens
+   - Click Add
+   - User: `root@pam`, Token ID: `terraform`
+   - Uncheck "Privilege Separation"
+   - Save the token secret (shown only once)
+
+2. **Configure credentials:**
+   ```bash
+   cd terraform
+   cp terraform.tfvars.example terraform.tfvars
+   # Edit terraform.tfvars with your Proxmox details
+   ```
+
+3. **Initialize OpenTofu:**
+   ```bash
+   tofu init
+   ```
+
+4. **Test connection:**
+   ```bash
+   tofu plan
+   ```
+
+## Files
+
+- `main.tf` - Provider configuration and test data source
+- `variables.tf` - Variable definitions
+- `terraform.tfvars.example` - Example credentials file
+- `terraform.tfvars` - Your actual credentials (gitignored)