Refactor systemctl services and timers

- Unified service templates into generic systemctl templates
- Introduced reusable filter plugins for script path handling
- Updated path variables and service/timer definitions
- Migrated roles (backup, cleanup, repair, etc.) to use systemctl role
- Added sys-daemon role for core systemd cleanup
- Simplified timer handling via sys-timer role

Note: This is a large refactor and some errors may still exist. Further testing and adjustments will be needed.

roles/svc-net-wireguard-plain/templates/script.sh.j2

@@ -0,0 +1,4 @@
+#!/bin/bash
+{% for internet_interface in internet_interfaces %}
+ip li set mtu 1400 dev {{internet_interface}}
+{% endfor %}