youtube-video-element: iframe allow omits `clipboard-write` and `web-share`, breaking the player's Share/Copy controls

[jeffsawyer]

The repo's packages/youtube-video-element/youtube-video-element.js has iframeAttrs, but the allow is missing tokens to match YouTube's official embed:

allow: "accelerometer; autoplay; clipboard-write; encrypted-media; fullscreen; gyroscope; picture-in-picture; web-share"