v0.1.47

history: a sprite's history as a line, and going to a step (#49)

Pixi now gives fizzy its history as a line (`historyLine`: each step's id and what it did, how
many are applied, a version that moves with it) and goes to any step on it (`historyGoTo`), so a
sprite gets fizzy's transport (undo and redo as seeks, the line to scrub) and its track can be
exported as a tape. Going to a step undoes or redoes there quietly: one move, not a toast for each
step on the way.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>