infra(sys-service): centralize async control + pre-deploy backup safeguard

- Added MODE_BACKUP to trigger backup before the rest of the deployment

- sys-ctl-bkp-docker-2-loc: force linear sync and force flush when MODE_BACKUP is true

- Unified name resolution via system_service_name across handlers and tasks

- Introduced system_service_force_linear_sync and system_service_force_flush (rename from system_force_flush)

- Drive async/poll via system_service_async/system_service_poll using omit when disabled

- Propagated per-role overrides (cleanup, repair, cert tasks) for clarity and safety

- Minor formatting and consistency cleanups

Why: Ensure the backup runs before the deployment routine to safeguard data integrity.

Refs: Conversation https://chatgpt.com/share/68de4c41-b6e4-800f-85cd-ce6949097b5e
Signed-off-by: Kevin Veen-Birkenbach <kevin@veen.world>

roles/sys-ctl-bkp-docker-2-loc/tasks/01_core.yml

@@ -19,6 +19,8 @@
   vars:
     system_service_copy_files:          false
     system_service_timer_enabled:       true
+    system_service_force_linear_sync:   true
+    system_service_force_flush:         "{{ MODE_BACKUP | bool }}"
     system_service_on_calendar:         "{{ SYS_SCHEDULE_BACKUP_DOCKER_TO_LOCAL }}"
     system_service_tpl_exec_start_pre:  '/usr/bin/python {{ PATH_SYSTEM_LOCK_SCRIPT }} {{ SYS_SERVICE_GROUP_MANIPULATION | join(" ")  }} --ignore {{ SYS_SERVICE_BACKUP_DOCKER_2_LOC }} --timeout "{{ SYS_TIMEOUT_BACKUP_SERVICES }}"'
     system_service_tpl_exec_start:      "/bin/sh -c '{{ BKP_DOCKER_2_LOC_EXEC }}'"