Single fullscreen player state everywhere (desktop/Android/iOS/feed) instead
of the old modal-vs-native-fullscreen split, with custom controls: draggable
timeline with buffered range, dynamically-escalating skip buttons (double-tap
zones too), per-video format switching, favorites, PiP with auto-PiP on
backgrounding, volume swipe, TikTok-style HUD auto-hide, and swipe-down/
back-button/close-button dismissal. Reels feed reuses the same skip/format/
PiP logic via the new customPlayer.js shared module.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
