AudioRouteCollector
Passive live collector for SignalCategory.Audio.
Snapshot collect reports output/input device counts and types, ringer mode, music-active state, speakerphone/Bluetooth-SCO routing and per-stream volumes via AudioManager. liveFlow streams audio-routing changes (audioSignalsFlow).
Privacy: audio device types can reveal connected accessories and volume/ringer settings are user preferences; no runtime permission is required for this metadata.