Initial Ansible automation for hobbs.farm infrastructure

Complete IaC covering:
- 14 roles: common, docker, traefik, vaultwarden, monitoring, media, matrix,
  home_assistant, frigate, adguard, gitea, semaphore, openclaw, security, backup
- Inventory for all hosts (Peggy, Bart, Yoda, NAS, Firewalla)
- Stack playbooks: core-infrastructure, monitoring, media, communication,
  automation, smarthome, security-hardening
- Maintenance playbooks: update-containers, backup, health-check
- Production Docker Compose templates with Traefik labels
- Security hardening (sysctl, auditd, UFW, fail2ban)
- Automated backups with retention policy

roles/backup/defaults/main.yml

@@ -0,0 +1,9 @@
+---
+backup_script_path: /usr/local/bin/homelab-backup.sh
+backup_schedule: "0 2 * * *"
+backup_retention_days: 30
+backup_sources:
+  - /data/docker-compose
+backup_destination: /mnt/nas/backups/{{ inventory_hostname }}
+backup_pre_commands: []
+backup_post_commands: []