Lets the Apple TV switch its HDMI output to match the playing video's
frame rate and dynamic range via AVDisplayManager.preferredDisplayCriteria,
driven from MPV's container-fps and video-params/gamma. Two opt-in toggles
(default off) live under Playback → Display on tvOS; both are no-ops on
other platforms. Anchor an AVKit class symbol so the linker keeps AVKit
linked — Swift only autolinks AVFoundation here, and without AVKit the
UIWindow.avDisplayManager category isn't loaded at runtime.
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