feat(services): refine split-horizon OIDC routing and harden nextcloud patch

- authentik: address the rewrite service by compose service name instead
  of a network alias on the public FQDN, which shadowed extra_hosts pins
  and broke OIDC discovery for c-ares-based (Node) resolvers
- homarr: add homarr_extra_hosts to pin the IdP FQDN to a LAN IP so OIDC
  discovery stays in-network while the issuer matches the browser-facing URL
- opnform: add opnform_oidc_sso_redirect_root to 302 the root URL to the
  SSO path (deep-links untouched, /login?bypass=1 break-glass); restart
  ingress via container restart so envsubst re-renders nginx.conf
- nextcloud: make the UserConfig sed workaround fail loud on upstream
  drift instead of silently skipping (nextcloud/server#59629)
- gitignore: exclude the local .ansible/ collection cache

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

@@ -26,6 +26,12 @@ services:
       AUTH_OIDC_AUTO_LOGIN: "{{ homarr_oidc_auto_login | default('false') }}"
     networks:
       - {{ homarr_traefik_network }}
+{% if homarr_extra_hosts | default([]) | length > 0 %}
+    extra_hosts:
+{% for h in homarr_extra_hosts %}
+      - "{{ h }}"
+{% endfor %}
+{% endif %}
     labels:
       - traefik.enable=true
       - traefik.docker.network={{ homarr_traefik_network }}