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-daemon/handlers/main.yml

@@ -35,14 +35,19 @@
     - reexec systemd manager
 
 - name: reload system daemon
-  command: systemctl daemon-reload
+  ansible.builtin.systemd:
+    daemon_reload: true
   become: true
-  listen: reload system daemon
+  listen:
+    - reload system daemon
+    - refresh systemctl service
   async: "{{ ASYNC_TIME if ASYNC_ENABLED | bool else omit }}"
   poll:  "{{ ASYNC_POLL if ASYNC_ENABLED | bool else omit }}"
 
 - name: reexec systemd manager
-  command: systemctl daemon-reexec
+  # Just execute this during reset, it has potential dangerous side effects
+  ansible.builtin.systemd:
+    daemon_reexec: true
   become: true
   listen: reexec systemd manager
   async: "{{ ASYNC_TIME if ASYNC_ENABLED | bool else omit }}"