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/systemd.py

@@ -9,7 +9,10 @@ class Systemd:
         self.log, self.sys, self.tpl, self.host = log, sys_, tpl, host
 
     def deploy_units(self, configs_subdir: str, vars: dict, dry_run: bool = False) -> None:
-        rendered = self.tpl.render_dir(configs_subdir, vars)
+        # Top-level, non-hidden files only — the bash glob ("$CONFIG_DIR"/* + [[ -f ]])
+        # never recursed nor picked up dotfiles like .gitkeep.
+        rendered = {rel: c for rel, c in self.tpl.render_dir(configs_subdir, vars).items()
+                    if "/" not in rel and not rel.startswith(".")}
         if not rendered:
             self.log.warn(f"No systemd units found under configs/{configs_subdir}.")
             return