fix: resolve 17 confirmed bash-parity drifts from port review

Adversarial parity review of every ported action against its bash source
confirmed 17 real behavioral drifts (of 22 claimed); all fixed here:

- tiers/chown: defaults were compositions/apex/tierN (one level too deep);
  now the tier roots. shared/ base reset is non-recursive again.
- compose: --dry-run was swallowed by argparse.REMAINDER; now stripped.
- host.write_file: rendered files land 0644 (tempfile's 0600 made fresh
  systemd units/crowdsec configs owner-only).
- systemd.deploy_units: top-level non-hidden files only.
- ufw: missing docker/host config dir exits 66; missing /etc/ufw target
  aborts; empty rules dir warns; dotfile .rules excluded.
- sync/packages: Telegram error-trap parity and failed notify exits 1.
  Same notify-failure exit for backup/run and sync/repository.
  repository regains the node-dir guard.
- tiers/useradd: no more secret-bearing .env.bak per run.
- tiers/link: EOF on confirm prompt declines and continues.
- extract-traefik-certs: sudo mkdir inside the notify envelope.
- generate-happ-subscriptions: realpath parent-exists guards + docker check.
- configure/crowdsec: bouncer install goes through install_packages.
- lint-docker-compose: malformed/unreadable anchor-IP inputs are lint errors.
- core compose: APEX_RESTIC_REPOSITORY now ?error; RESTIC_COMPRESSION
  per-node via APEX_RESTIC_COMPRESSION (default auto).
- sys.service_exists line-anchored; tpl docstring corrected.

engine/lib/sys.py

@@ -31,7 +31,8 @@ class Sys:
     def service_exists(self, name: str) -> bool:
         cp = self.run(["systemctl", "list-unit-files", "--type=service"],
                       check=False, capture=True)
-        return f"{name}.service" in (cp.stdout or "")
+        return any(line.startswith(f"{name}.service")
+                   for line in (cp.stdout or "").splitlines())
 
     def service_is_active(self, name: str) -> bool:
         return self.ok(["systemctl", "is-active", "--quiet", name])