chore: add AGENTS.md for opencode agents

# Agents

This role configures Unbound as a local DNS resolver.

## Role Analysis

- **Type**: Infrastructure service role (DNS)

- **OS Support**: Alpine 3.22, Debian 12

- **Deployment Method**: Direct (not Docker-based)

- **Scope**: DNS server installation and configuration

## Tasks

1. **install** - Installs Unbound DNS

2. **config** - Configures DNS zones and forwarding

## Testing

```bash

ansible-lint

molecule test

```