Since edit permissions landed (8c82877) the canvas ignored every pointer
on placed objects for anyone who can't edit, lineups included. Opening a
lineup is the only way to see its media, so viewers, and signed-out
readers on a share link, could see lineup lines but never their images.

The block now covers everything placed except lineup ends. A viewer can
tap an end to open its lineups and hover it for its note; they get no
drag, no right-click edit menu, no hover delete target, no Edit or
Delete in the media viewer or panel, and an open panel no longer tells
teammates they are editing it.

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