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/traefik/tasks/main.yml

@@ -1,4 +1,13 @@
 ---
+- name: Create Traefik log directory
+  ansible.builtin.file:
+    path: /var/log/traefik
+    state: directory
+    owner: root
+    group: root
+    mode: "0755"
+  tags: traefik
+
 - name: Create Traefik data directory
   ansible.builtin.file:
     path: "{{ traefik_data_dir }}"