An image's id also names its picture on the server, so a copy, which gets
an id of its own, first has the server give that id the original's
picture (images:copyAsset, sharing the stored bytes), and only then is
sent. An image still uploading, or one the cloud cannot show, is not
copied, and a toast says why.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>