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/monitoring/templates/alertmanager.yml.j2

@@ -0,0 +1,29 @@
+global:
+  resolve_timeout: 5m
+{% if alertmanager_smtp_host is defined and alertmanager_smtp_host %}
+  smtp_smarthost: "{{ alertmanager_smtp_host }}"
+  smtp_from: "{{ alertmanager_smtp_from }}"
+{% endif %}
+
+route:
+  group_by: ["alertname", "instance"]
+  group_wait: 30s
+  group_interval: 5m
+  repeat_interval: 4h
+  receiver: default
+
+receivers:
+  - name: default
+{% if alertmanager_slack_webhook is defined and alertmanager_slack_webhook %}
+    slack_configs:
+      - api_url: "{{ alertmanager_slack_webhook }}"
+        channel: "#alerts"
+        send_resolved: true
+{% endif %}
+
+inhibit_rules:
+  - source_match:
+      severity: critical
+    target_match:
+      severity: warning
+    equal: ["alertname", "instance"]