fix(backup): bring act-runner back up on every termination path

If ci-backup-template.service is killed mid-run (SIGTERM), the Python
finally block that restarts act-runner.service is skipped. A subsequent
backup then finds the runner already inactive, _stop_runner returns
False, and the finally restart is gated off — leaving the runner down
indefinitely (incident: 21 mag 2026, runner stayed off ~80 min).

Add ExecStopPost=-/bin/systemctl start act-runner.service so systemd
guarantees the runner is restarted regardless of how the unit exits
(success, failure, signal). The `-` prefix preserves the unit's own
exit status.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deploy/systemd/ci-backup-template.service

@@ -9,6 +9,11 @@ User=root
 EnvironmentFile=/etc/ci/environment
 WorkingDirectory=/opt/ci/local-ci-cd-system
 ExecStart=/opt/ci/venv/bin/python -m ci_orchestrator template backup --all-templates
+# Safety net: bring act-runner.service back up on any exit path (success,
+# failure, signal). The Python `finally` block can be skipped if the
+# service is killed mid-run, and a runner left stopped by a killed
+# backup would cause the next backup to skip the restart too.
+ExecStopPost=-/bin/systemctl start act-runner.service
 TimeoutStartSec=4h
 IOSchedulingClass=best-effort
 IOSchedulingPriority=7