#290 added addReplays, the shared way to add replay files with a toast
and a reveal of the new tiles. Replays opened from anywhere now go through
it: one opens in the viewer, several land on the tab with the reveal, and
files that aren't readable replays only get its toast, without leaving
the editor or the tab the user is on. The Replays tab's own drop target
passes only the non-replay files of a drop to addReplays, since the
window target takes the replays.

Opens now wait in a list rather than a chained future, and one that
throws is reported instead of stopping the ones behind it.

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