fix(player): prewarm hidden YT player (autoplay within gesture)
The YT player was only created on click (cold) → by the time it was ready
the click gesture had expired → YouTube blocked autoplay (flaky: only worked
if the player happened to be warm). Now embed-player prewarms the player as
soon as an audio-only YT embed/album renders
(pcmsAudioPlayer.prewarmYouTube), so the first click falls within the
gesture. busters audio-player.js?v=26, embed-player.js?v=15.
Co-Authored-By: Claude <noreply@…>