iframe and bypass host fixes

[ehfeng]

Accidentally had hypeship grouped them into one PR (used private thread instead of just tagging #docs).

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Note

Low Risk
Low risk: documentation-only changes that adjust guidance and fix a link, with no runtime or API behavior impact.

Overview
Adds a new iframe embedding tip to browsers/live-view.mdx, covering Safari focus requirements for keyboard input and the allow="autoplay; clipboard-read; clipboard-write" attribute for clipboard sharing.

Fixes the March 6 changelog entry to point proxy-bypass-hosts to the correct URL anchor.

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