Sensor Location Parameter for Pleth PTT

A sensor location dropdown (finger, ear, toe, forehead) that adjusts the default PTT range to reflect the chosen anatomy: - Ear: shorter PTT (proximal to heart) - Finger: middle range (current default) - Toe: longer PTT (most distal) - Forehead: shorter PTT (reflectance oximetry) Useful for advanced scenarios that simulate sensor placement decisions or teach the physiological basis of PTT differences by site. Deferred from v1 due to added complexity.