PiP & Background Video/iPlayer

- Added a playback queue (playlist) that lets you continue playing videos across folders, along with a per-video notes feature. - Added a setting to choose the on-screen layout when rotating video playback ("full screen" or "bar visible"). - Fixed an issue where, with "Background behavior" set to "background audio," playback would stop when switching to another app or locking the screen. - Added lock screen support for the seek bar, next/previous video switching, and thumbnail display during background audio playback. - Fixed sluggish screen transitions right after unlocking with a passcode. - Added a "make visible in the Files app" setting (independent of the passcode setting). - Improved shuffle playback so it's less likely to immediately repeat the video that just played. - Fixed several crashes that could occur while reordering the folder list, among other operations.