audio-bridge: full pipewire-pulse.conf with context.modules

Alpine's pipewire-pulse is a minimal build that doesn't load
/usr/share/pipewire/pipewire-pulse.conf (no context.modules).
Provide a full config that includes all required modules.

infra/audio-bridge/pipewire-pulse.conf

@@ -1,8 +1,45 @@
-# Custom PipeWire-Pulse config: override server.address to add TCP 4713 listener.
-# This file is loaded from /etc/pipewire/pipewire-pulse.conf and overrides
-# defaults from /usr/share/pipewire/pipewire-pulse.conf.
-#
-# PA clients (librespot, mopidy) connect via tcp:127.0.0.1:4713.
+# PipeWire-Pulse config: full default config + TCP 4713 listener.
+# This is a complete config (not an override); we add tcp:4713 alongside
+# the default unix:native socket so PA clients (librespot, mopidy) can
+# connect from sibling containers via PULSE_SERVER=tcp:127.0.0.1:4713.
+
+context.properties = {
+    ## Configure properties in the system.
+    #mem.warn-mlock  = false
+    #mem.allow-mlock = true
+    #mem.mlock-all   = false
+    #log.level       = 2
+
+    #default.clock.quantum-limit = 8192
+}
+
+context.spa-libs = {
+    audio.convert.* = audioconvert/libspa-audioconvert
+    support.*       = support/libspa-support
+}
+
+context.modules = [
+    { name = libpipewire-module-rt
+        args = {
+            nice.level   = -11
+        }
+        flags = [ ifexists nofail ]
+    }
+    { name = libpipewire-module-protocol-native }
+    { name = libpipewire-module-client-node }
+    { name = libpipewire-module-adapter }
+    { name = libpipewire-module-metadata }
+
+    { name = libpipewire-module-protocol-pulse
+        args = {
+            # server.address is set in pulse.properties below
+        }
+    }
+]
+
+pulse.cmd = [
+    { cmd = "load-module" args = "module-always-sink" flags = [ ] }
+]
 
 pulse.properties = {
     server.address = [