Alpine's pipewire-pulse binary is stripped (-a option removed); the
only way to configure listening address is via config file. Add
/etc/pipewire/pipewire-pulse.conf that overrides server.address to
include tcp:4713 alongside the default unix:native socket.
Server addresses now:
- unix:native (for in-container clients)
- tcp:4713 (for sibling containers connecting via PULSE_SERVER env var)
