A same-picture enqueue that landed, or was still being saved, while the
served check was out could be deleted or overwritten by the stale job.
The removal and the failure write now each act only if the job is still
the one the check started from, checked where writes are serialized.

The upload toast's state is no longer disposed: a dismissed toast can
still build with it, which failed this file's tests in CI.

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