Harden against bot floods and add post-provisioning service check

- Traefik rate-limits all routes (60 req/min standard, 300 for Nextcloud)
  and writes access logs to /var/log/traefik/access.log
- Fail2ban watches Traefik access logs and bans IPs after 10 x 403/404
  within 60 s for 24 h
- Nextcloud html directory created as www-data (UID 33) so Apache can
  process .htaccess and serve requests correctly
- scripts/check-services.sh verifies all seven endpoints return the
  expected HTTP status after provisioning

ansible/roles/base/handlers/main.yml

@@ -3,3 +3,8 @@
   ansible.builtin.service:
     name: ssh
     state: restarted
+
+- name: Restart fail2ban
+  ansible.builtin.service:
+    name: fail2ban
+    state: restarted