Refactor systemd handling

- sys-ctl-rpr-btrfs-balancer: suppress service flush for btrfs balancer (too expensive to run each play)
- sys-daemon: replace raw systemctl calls with ansible.builtin.systemd (daemon_reload, daemon_reexec)
- sys-service: split handler into 'Enable systemctl service' and 'Set systemctl service state', add become, async/poll, suppress flush guard

Conversation: https://chatgpt.com/share/68c2f7a6-6fe4-800f-9d79-3e3b0ab4a563

roles/sys-service/handlers/main.yml

@@ -1,9 +1,19 @@
-- name: "refresh systemctl service"
+- name: "Enable systemctl service"
   systemd:
     name: "{{ system_service_id | get_service_name(SOFTWARE_NAME) }}"
-    daemon_reload: yes
     enabled: yes
+    daemon_reload: true
+  become: true
+  async:  "{{ ASYNC_TIME if ASYNC_ENABLED | bool else omit }}"
+  poll:   "{{ ASYNC_POLL if ASYNC_ENABLED | bool else omit }}"
+  listen: refresh systemctl service
+
+- name: "Set systemctl service state"
+  systemd:
+    name: "{{ system_service_id | get_service_name(SOFTWARE_NAME) }}"
     state: "{{ system_service_state }}"
+  become: true
   async:  "{{ ASYNC_TIME if ASYNC_ENABLED | bool else omit }}"
   poll:   "{{ ASYNC_POLL if ASYNC_ENABLED | bool else omit }}"
   when:   not (system_service_suppress_flush | bool)
+  listen: refresh systemctl service