The macOS controls stack (MacOSPlayerControlsView + MacOSControlBar)
never read playerState.isControlsLocked, so locking via the settings
sheet had no effect: buttons, the scrubber, the volume slider, and the
AppKit keyboard shortcuts all kept working.
When locked, dim and disable transport, volume, the progress bar,
queue, the more menu, PiP, the pin/floating toggle, and the title-tap
details button; ignore playback keyboard shortcuts (space/arrows/mute)
while keeping F/Esc for fullscreen. Settings and Close stay enabled so
the user can reopen Settings to unlock.
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