Per-Beat Pleth PTT Variability

Real Pulse Transit Time (PTT) varies slightly beat-to-beat due to respiratory variation and other physiological factors. Adding subtle randomization of +/-10-20 ms per beat would increase the realism of the pleth waveform. In v1, PTT is a fixed value per the slider setting. This feature adds optional per-beat variability around the set value. Deferred from v1 - low priority but meaningful for advanced realism. Can be implemented as an optional toggle for instructors who want maximum physiological fidelity.