init: 20_audiod.service oneshot_async to not block boot on missing audio hw

init.d/20_audiod.service

@@ -6,4 +6,9 @@ requires_weak = [
 
 [service]
 cmd = "audiod"
-type = { scheme = "audio" }
+# oneshot_async, NOT a blocking scheme unit: as type={scheme="audio"} init
+# waits (call_ro) for audiod to hand back its scheme cap fd, but audiod does
+# not signal readiness on a machine with no audio hardware, so init blocks
+# here forever — before the console/login stack. Audio is not on the path to
+# login, so start it non-blocking (matches the redbear-mini audiod unit).
+type = "oneshot_async"