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/files/jail.d/traefik.conf

@@ -0,0 +1,8 @@
+[traefik]
+enabled  = true
+port     = http,https
+filter   = traefik
+logpath  = /var/log/traefik/access.log
+maxretry = 10
+findtime = 60
+bantime  = 86400