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/homarr/defaults/main.yml

@@ -15,6 +15,10 @@ homarr_db: "{{ homarr_appdata_dir }}/db/db.sqlite"
 
 # Service configuration
 homarr_domain: "homarr.local.test"
+# Additional hostnames the homarr router answers on (e.g. an internal
+# *.int.* FQDN so a DMZ reverseproxy can hit a backend hostname covered
+# by the cert).
+homarr_extra_domains: []
 homarr_image: "ghcr.io/homarr-labs/homarr:latest"
 homarr_port: 7575
 homarr_use_docker: false