probeSensorInventoryHash
Hashes the (bounded) list of sensors reported by SensorManager.
The vendor/name/type/id tuple of each sensor is joined and SHA-256 hashed, yielding a compact fingerprint of the device's sensor inventory. Reads via SensorManager.getSensorList, which requires no permission.
Return
SHA-256 hex of the sensor inventory, or null if no sensors are present.
Parameters
sm
Sensor manager to enumerate.
max
Maximum number of sensors to include (bounds work on unusual devices).