The previous commit() just returned true, relying on
createDragSession.terminate() to resumeHistory. But that alone never
captures the drag in zundo's pastStates — the pause window's mutations
are skipped entirely. After commit, Ctrl-Z jumped past the curve *and*
past the prior fence creation.
Adds the same dance now used by move-endpoint: restoreAll →
resumeHistory → re-apply the final draft. Zundo records one undo step
for the whole drag. cancel() becomes a no-op (orchestrator's
restoreAll covers it).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
