Allow non-LAN proxy binding for Docker host-gateway clients

Portless 0.15.6 binds non-LAN proxies only to 127.0.0.1 and ::1 (source). Containers reaching the host through Docker host-gateway therefore get ECONNREFUSED; --lan is not equivalent because it enables mDNS and forces .local.

Please add an explicit non-LAN bind option that listens on 0.0.0.0 and :: without enabling LAN discovery or changing the TLD. Please also expose the effective bind mode in proxy status --json so managed clients can reconcile an existing daemon.