Add backup role to deploy hdd-backup.sh and cron to london-b (#16)

Captures the existing /root/scripts/backup.sh and its 22:00 daily cron
job as an Ansible role so it's managed via pez-infra deploys.

Refs: PESO-95

ansible/deploy.yml

@@ -53,12 +53,13 @@
   roles:
     - role: caddy
 
-# london-b: Docker services (storage, apps)
+# london-b: Docker services (storage, apps) + backups
 - name: "Stage 4b: Docker services (london-b)"
   hosts: london-b
   tags: [services, london-b]
   roles:
     - role: docker_services
+    - role: backup
 
 # nuremberg-a: Mail (poste.io via Docker)
 - name: "Stage 4c: Mail (nuremberg-a)"

ansible/roles/backup/tasks/main.yml

@@ -0,0 +1,22 @@
+---
+# Deploy backup script and cron job for rclone-to-B2 backups.
+
+- name: Ensure scripts directory exists
+  ansible.builtin.file:
+    path: /root/scripts
+    state: directory
+    mode: '0755'
+
+- name: Deploy backup script
+  ansible.builtin.copy:
+    src: "{{ playbook_dir }}/scripts/hdd-backup.sh"
+    dest: /root/scripts/backup.sh
+    mode: '0755'
+
+- name: Configure backup cron job
+  ansible.builtin.cron:
+    name: "HDD backup to B2"
+    minute: "0"
+    hour: "22"
+    job: "/root/scripts/backup.sh"
+    user: root