Ports openwakeword 0.6.0's AudioFeatures._streaming_features() and
Model.predict() to C# / Microsoft.ML.OnnxRuntime 1.26.0.
Bug fixed vs plan: actual melspectrogram.onnx output shape is
(1, 1, n_frames, 32) — n_frames lives at Dimensions[2], not [1].
Access pattern corrected to melOut[0, 0, f, b].
Smoke test on Pi: 25/50 non-zero silence scores, max ≈ 0.000064
(matches Python reference: 45/50 non-zero, same magnitude).
"Predict pipeline ran without throwing." confirmed.
tes