feat(services): multi-domain routing, split-horizon and OIDC hardening

Bundle of cross-role changes for the gymb services deployment:

- Traefik routers: OR-combine opnform/homarr/bookstack Host rules with new
  *_extra_domains (internal *.int.* FQDNs for a DMZ reverseproxy), and emit
  tls.certresolver only when traefik_cert_mode == acme (drawio, homarr,
  opnform, send).
- Split-horizon: bookstack_extra_hosts / opnform_extra_hosts add container
  /etc/hosts overrides so containers reach the IdP public FQDN over the LAN.
- bookstack: assert the OIDC issuer resolves concretely (reject "//v2.0"),
  allowing non-Entra IdPs that override bookstack_oidc_issuer.
- homarr: derive the bcrypt salt from the password digest so the admin hash
  is idempotent — no spurious template changes / container restarts.
- opnform: PATCH an existing OIDC connection instead of skipping (applies
  corrected inventory on re-run); add OIDC_FORCE_LOGIN (enabled only after
  bootstrap) and an optional direct-SSO ingress entrypoint.

Docs: READMEs and meta/argument_specs.yml updated for all new variables.

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

@@ -45,13 +45,19 @@ services:
     networks:
       - {{ bookstack_traefik_network }}
       - internal
+{% if bookstack_extra_hosts | length > 0 %}
+    extra_hosts:
+{% for host in bookstack_extra_hosts %}
+      - "{{ host }}"
+{% endfor %}
+{% endif %}
     depends_on:
       {{ bookstack_service_name }}-db:
         condition: service_healthy
     labels:
       - "traefik.enable=true"
       - "traefik.docker.network={{ bookstack_traefik_network }}"
-      - "traefik.http.routers.{{ bookstack_service_name }}.rule=Host(`{{ bookstack_domain }}`)"
+      - "traefik.http.routers.{{ bookstack_service_name }}.rule={% set _all_domains = [bookstack_domain] + (bookstack_extra_domains | default([])) %}{% for d in _all_domains %}Host(`{{ d }}`){% if not loop.last %} || {% endif %}{% endfor +%}"
       - "traefik.http.routers.{{ bookstack_service_name }}.entrypoints=websecure"
       - "traefik.http.routers.{{ bookstack_service_name }}.tls=true"
       - "traefik.http.routers.{{ bookstack_service_name }}.tls.certresolver={{ bookstack_traefik_certresolver }}"