v0.2.1

Fix: with a fast adapter setup(), the pre-roll trim point could land inside the magenta calibration flash, leaving solid-magenta opening frames (which also became the video thumbnail). The record phase now holds briefly after the flash and after setup so the final video opens on the settled app; the post phase clamps the trim point to never start before the flash has cleared. The e2e suite now asserts the output contains no flash. Demo assets regenerated.