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/README.md

@@ -46,6 +46,7 @@ See `defaults/main.yml` for the full list. Most useful overrides:
 | Variable | Default | Purpose |
 |---|---|---|
 | `homarr_domain` | `homarr.local.test` | Traefik Host rule |
+| `homarr_extra_domains` | `[]` | Extra Host-rule hostnames (OR-combined), e.g. internal `*.int.*` FQDN |
 | `homarr_base_url` | `https://home.local.test` | NEXTAUTH_URL / BASE_URL |
 | `homarr_auth_providers` | `credentials` | `credentials`, `oidc`, or both |
 | `homarr_oidc_issuer` | empty | Identity provider issuer URL |