Pin the built-in card to S16_LE for PipeWire

The ADSP front-end advertises S24_LE and then garbles it: playback runs
without an error, consumes data at rate, powers every DAPM widget, and
produces ~-48 dB of near-silence. PipeWire prefers the widest advertised
format, so every PipeWire client was inaudible while aplay and
speaker-test, which default to S16_LE, worked. One wireplumber rule pins
the format until the q6asm handling is fixed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011XgGF5wfxLDAybVnNz6eNQ

overlay/etc/wireplumber/wireplumber.conf.d/51-c630-alsa.conf

@@ -0,0 +1,20 @@
+# The sdm845 ADSP front-end advertises S24_LE (24-bit samples in 32-bit
+# containers) and then garbles it — playback runs without a single error,
+# consumes data at the right rate, powers every DAPM widget, and produces
+# roughly -48 dB of near-silence. PipeWire prefers the widest format a device
+# offers, so out of the box every PipeWire client is inaudible while
+# aplay/speaker-test, which default to S16_LE, work fine.
+#
+# Pin the built-in card to S16_LE until the q6asm format handling is fixed.
+monitor.alsa.rules = [
+  {
+    matches = [
+      { node.name = "~alsa_output.platform-sound.*" }
+    ]
+    actions = {
+      update-props = {
+        audio.format = "S16LE"
+      }
+    }
+  }
+]