MotionCollector
Permissioned collector for SignalCategory.Motion.
Reports activity-recognition / body-sensors grant state, heart-rate sensor presence and a coarse step-count bucket via SensorManager. The step read requires ACTIVITY_RECOGNITION; without it the bucket is reported as permission_required.
Privacy: activity/step data is behaviorally identifying and health-adjacent; only a coarse bucket (never the raw step stream) is emitted. Gated behind PermissionKind.Motion.