An incomplete startup command list consumed both layout detection and the
one-time DeviceSink scan, leaving valid SDK 4 audio frames permanently
silent. Keep both decisions pending until a supported layout walks the
whole list, as proposed in PR #331.
Extend the reproducer with valid-first and incomplete-startup stereo PCM
checks for SDK 4, 6, 16 and 21, and document the finding.
Co-authored-by: aldomrodriguez <rodriguez.aldo.91@hotmail.com>