audio-bridge: custom pipewire-pulse.conf with TCP 4713 listener

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)

infra/audio-bridge/Dockerfile

@@ -19,6 +19,7 @@ RUN apk add --no-cache \
 
 COPY entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh
+COPY pipewire-pulse.conf /etc/pipewire/pipewire-pulse.conf
 
 # D-Bus socket dir for bluetoothd / wireplumber / pipewire
 VOLUME ["/run/dbus", "/run/user/0"]