Manage own borgmatic systemd service and timer

Ship borgmatic.service and borgmatic.timer from the backup role instead
of relying on the package-provided units. The units are deployed to
/etc/systemd/system (overriding the package units), with a configurable
schedule via role defaults.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

roles/backup/tasks/main.yml

@@ -75,6 +75,29 @@
         group: root
         mode: '0640'
 
+    - name: Deploy borgmatic systemd service (overrides package unit)
+      ansible.builtin.template:
+        src: borgmatic.service.j2
+        dest: /etc/systemd/system/borgmatic.service
+        owner: root
+        group: root
+        mode: '0644'
+      register: _borgmatic_service_unit
+
+    - name: Deploy borgmatic systemd timer (overrides package unit)
+      ansible.builtin.template:
+        src: borgmatic.timer.j2
+        dest: /etc/systemd/system/borgmatic.timer
+        owner: root
+        group: root
+        mode: '0644'
+      register: _borgmatic_timer_unit
+
+    - name: Reload systemd if units changed
+      ansible.builtin.systemd:
+        daemon_reload: true
+      when: _borgmatic_service_unit is changed or _borgmatic_timer_unit is changed
+
     - name: Enable and start borgmatic timer
       ansible.builtin.systemd:
         name: borgmatic.timer