Redesign tvOS player controls with centered transport cluster

- Move Close to a top-right circular icon; bottom row reorganizes into
  left (Settings/Info/Comments), center transport (Previous/PlayPause/Next),
  and right (Queue) clusters with equal side frames so transport stays
  geometrically centered.
- Introduce a circular icon-only `TVTransportButtonStyle` (primary variant
  for Play/Pause) mirroring the new Close button look.
- Always render Previous/Next so Play/Pause position is fixed; dim and
  disable when unavailable.
- Share `isTransportDisabled` on `PlayerState` and reuse it on iOS and
  tvOS; apply it (plus symbol replace transition) to the tvOS Play/Pause
  button.

Yattee/Views/Player/tvOS/TVPlayerView.swift

@@ -17,6 +17,7 @@ enum TVPlayerFocusTarget: Hashable {
     case commentsButton
     case debugButton
     case playPrevious
+    case playPauseButton
     case playNext
     case closeButton
     case queueButton