THALis: retaining raw and overlaid video

keep raw video AND overlay. rerunning the tracker later is much easier if i haven't baked its guesses into the only copy

archived change (a932083): CameraRecorder.jsx saves the unprocessed webcam feed alongside the MediaPipe-overlay recording.

why retain both: the overlay is convenient for inspection, while raw frames allow hand tracking to be rerun or reviewed independently of the original landmarks/rendering. A rendered skeleton is a model output, not part of the original camera measurement.

Hand-landmark overlay

• review questions: do raw and overlay files begin at the same instant and have the same effective frame timing? How are dropped frames or tracker failures represented? Does each landmark CSV identify the corresponding frame/session?

• reference record: pair the raw video, overlay video, landmark CSV and EEG/cue files by an explicit trial identifier. The archive records this preservation feature, but does not by itself demonstrate millisecond-level synchronization. Public notes should link to the code/configuration rather than expose participant video.

• archived code references: a932083.