iOS overlay — sourceopen isolation probe

Goal: find which video-element setup lets iOS open the MediaSource (the shipped overlay stalls because sourceopen never fires). The on-load variants start automatically; then tap Run gesture variants. Wait ~6s after each and read the table. Screenshot it.

sourceopen = iOS opened the MediaSource (the current blocker). videoWidth>0 = a frame decoded = full pipeline works. A "Pop" button appears for any variant that armed — tap it to confirm PiP floats.