Persistent per-platform mode that plays only the audio track to save
bandwidth and speed up loads. When enabled, stream selection picks the
best audio-only stream (preferred language, codec, bitrate) and never
fetches the video URL; toggling mid-video reloads at the current
position using the quality-switch path (live vid=no toggling is avoided
due to A/V desync).
- Toggle row in the player quality/settings sheet on iOS, macOS and
tvOS, next to lock controls
- New audioMode control button type (red when active) for player
controls and mini player layouts
- Picking a video quality explicitly turns the mode off; audio track
picks keep it on and now work while audio-only is playing
- Stream URL refresh preserves audio-only playback instead of
resurrecting video
- Queue preloads and history entries resolved before a toggle are
discarded so selection re-runs with the current mode
- tvOS player shows the video thumbnail instead of a black screen
during audio-only playback
- PiP button hidden for audio-only streams
Reset isCommentsExpanded and commentsFrame on the NavigationCoordinator
directly when the portrait panel is dismissed, since PortraitDetailsPanel
owns its own @State that doesn't sync back through .onChange during dismiss.
Also track comments overlay frame via GeometryReader so the dismiss gesture
can allow swipes outside the comments area instead of blanket-blocking.
