add n8n workflow automation and fix cloud backup rsync

- Add n8n container (n8nio/n8n:2.11.3) with Caddy reverse proxy at n8n.debyl.io
- Add --exclude .ssh to cloud backup rsync to prevent overwriting
  authorized_keys on TrueNAS backup targets

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ansible/roles/podman/templates/nextcloud/cloud-backup.sh.j2

@@ -1,4 +1,4 @@
 #!/bin/bash
 set -euo pipefail
-rsync -az -e "ssh -i {{ ssh_key_path }} -o StrictHostKeyChecking=accept-new" \
+rsync -az --exclude .ssh -e "ssh -i {{ ssh_key_path }} -o StrictHostKeyChecking=accept-new" \
   {{ data_path }}/ {{ ssh_user }}@truenas.localdomain:{{ remote_path }}/