fix(send): use Traefik v3 OR-syntax for multi-domain Host rule

The router rule joined send_domains with ', ' which is the v2 syntax
('Host(`a`, `b`)'). Traefik v3 expects each Host() to be its own
matcher joined with the explicit '||' OR operator. With v3 the comma
form is silently ignored — only the first host actually matches.

Match the pattern already used in the authentik, drawio and nextcloud
roles in this collection.

roles/send/templates/docker-compose.yml.j2

@@ -45,7 +45,7 @@ services:
     labels:
       - traefik.enable=true
       - traefik.docker.network={{ send_traefik_network }}
-      - traefik.http.routers.{{ send_service_name }}.rule=Host({% for d in send_domains %}`{{ d }}`{% if not loop.last %}, {% endif %}{% endfor %})
+      - traefik.http.routers.{{ send_service_name }}.rule={% for d in send_domains %}Host(`{{ d }}`){% if not loop.last %} || {% endif %}{% endfor +%}
       - traefik.http.services.{{ send_service_name }}.loadbalancer.server.port={{ send_port }}
 {% if send_use_ssl %}
       - traefik.http.routers.{{ send_service_name }}.entrypoints=websecure