feat(backend): identity advertises http_port (HTTP_PORT, default 80)

The native app downloads per-venue UI bundles from the plain-HTTP LAN port
(integrity via the sha256 in the manifest it fetched over pinned TLS), so it
needs to know the published port. compose passes HTTP_PORT to the backend.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker-compose.yml

@@ -12,6 +12,7 @@ services:
       - VERSION=${VERSION:-0.0.0}
       - HOST_IP=${HOST_IP:-}
       - TLS_PORT=${TLS_PORT:-8443}   # published port of the proxy's TLS entry (advertised to the app)
+      - HTTP_PORT=${HTTP_PORT:-80}   # published plain-HTTP LAN port (app downloads UI bundles from it)
       - MASTER_USERNAME=${MASTER_USERNAME:-}
       - MASTER_PASSWORD=${MASTER_PASSWORD:-}
     volumes: