Clicking a snapshot now selects it (highlighted in place of the current
state) until the history moves on. With a snapshot selected the footer's
trash runs history.deleteSnapshot instead of history.deleteState, as in
Photoshop. Snapshot rows and past state rows can also be dragged onto
the trash to delete them.
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>