feat(demo): add full inventories for mbazürich and phbern

Both demo sites had only a hosts.yml, so every role ran on its
defaults (authentik.local.test etc.) and nothing was reachable under
the real FQDN. Add the complete group_vars + host_vars analogous to
gymburgdorf, with the mbaz.souveredu.ch / phbe.souveredu.ch domain
bases, matching Bao mounts, DMZ split-horizon (public + *.int.*),
authentik OIDC/LDAP/proxy outposts, nextcloud with S3+LDAP+OIDC,
collabora, drawio, garage, send, opnform, homarr and bookstack.

authentik_domains lists the *.int.* name too so Traefik requests a
cert the DMZ can verify; the storage proxy outpost carries a config
block (required by the outpost blueprint serializer).

inventories/demo-mbazürich/host_vars/reverseproxy/traefik.yml

@@ -0,0 +1,22 @@
+---
+traefik_mode: dmz
+
+# The DMZ traefik discovers which services to expose by reading
+# traefik_dmz_exposed_services from each backend host's host_vars
+# (application/traefik.yml, storage/traefik.yml). See the role's
+# tasks/main.yml — set_fact "Build service registry from backend
+# servers (DMZ mode)".
+
+# From the DMZ network the public ns1 IP (193.43.183.169) is not
+# reachable on port 53, but the internal address (172.16.9.169) is.
+# Override the group-level traefik_acme_dns_nameserver from bao so
+# lego's RFC2136 updates land at the internal interface. The TSIG
+# key/secret are the same; only the transport target changes.
+traefik_acme_dns_nameserver: "172.16.9.169"
+
+# Lego's propagation check normally polls the NS hostnames listed in
+# the zone's SOA (ns1.digitalboard.ch.) — which resolves to the
+# public IP that's unreachable from this DMZ host. Skip that check;
+# lego still polls via the resolver above before asking LE to
+# validate.
+traefik_acme_disable_ans_checks: true