An empty text/plain paste previously returned before preventDefault, so
a clipboard carrying only richer types could have its converted text
inserted into the hidden textarea and leak through onInput without
bracketed-paste encoding — potentially alongside the async clipboard
read's delivery. The default is now always suppressed; the paste event
and the clipboard read remain the only delivery paths, still
deduplicated by the race token.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>