harden nextcloud backups: db dumps, alerting, drift fix

The data-only rsync left no way to restore a working instance: mysql/ and
config/ were never backed up, so a recovery would have files but no shares,
users or metadata. Dump the database before syncing files (a DB older than
the files is repairable with occ files:scan; a newer one references blobs
that never made it into the backup) and ship config/ alongside it.

Capture the --chmod=Du=rwx,Dgo=rx flag that had been hand-added to the
deployed skudak-cloud script. It was outside git, so every deploy silently
reverted it. It now lives in backup_rsync_extra_args.

Add OnFailure= alerting. The units failed silently before, which is how an
iDrive sync failure sat unnoticed since May. msmtp rather than the esmtp
already installed: the OpenSRS relay is port 465 (implicit TLS) and libesmtp
only speaks STARTTLS.

Exclude nextcloud.log* from the sync and cap log_rotate_size. skudak-cloud
was running at loglevel 0 and had written a 64 GB log that was being rsynced
and pushed to S3; set it to 2 to match the home instance.

Stagger the timers (04:00 / 04:30) so both finish before the 05:00 TrueNAS
snapshot task, and bound TimeoutStartSec so a wedged rsync cannot leave the
unit activating forever and skip every subsequent trigger.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

ansible/roles/podman/tasks/containers/home/cloud.yml

@@ -84,10 +84,24 @@
   vars:
     container_name: cloud
 
+# Unbounded by default: nextcloud.log.1 had reached 1.12 GB and was being
+# rsynced to TrueNAS and pushed to S3 on every run. Cap at 10 MiB.
+- name: cap nextcloud log rotation size for cloud
+  become: true
+  become_user: "{{ podman_user }}"
+  ansible.builtin.command: >
+    podman exec -u www-data cloud
+    php occ config:system:set log_rotate_size --value 10485760 --type integer
+  register: cloud_log_rotate
+  changed_when: "'System config value log_rotate_size' in cloud_log_rotate.stdout"
+  failed_when: false
+
 - include_tasks: containers/cloud-backup.yml
   vars:
     backup_name: cloud
     data_path: "{{ cloud_path }}/data"
+    config_path: "{{ cloud_path }}/config"
+    db_container: cloud-db
     ssh_key_path: /etc/ssh/backup_keys/cloud
     ssh_key_content: "{{ cloud_backup_ssh_key }}"
     ssh_user: cloud