Turn audio soft mixing into an opt-in toggle

It causes issues on some machines, but is required on the Asus G14

default/wireplumber/wireplumber.conf.d/alsa-soft-mixer.conf

@@ -0,0 +1,18 @@
+## Use software volume control for all ALSA devices.
+## This prevents hardware mixer quirks (like muffled audio on Realtek codecs)
+## and provides consistent volume behavior across all hardware.
+
+monitor.alsa.rules = [
+  {
+    matches = [
+      {
+        device.name = "~alsa_card.*"
+      }
+    ]
+    actions = {
+      update-props = {
+        api.alsa.soft-mixer = true
+      }
+    }
+  }
+]