Introduce a leafer-ui canvas layer that mirrors rendered nodes and drives
viewport, node-drag, and alignment-guide updates imperatively, committing
React state on idle via startTransition to keep pan/zoom/drag at 60fps. Wire
the imperative viewport through wheel zoom, zoom-to, fit-view, and panning.
Add a dedicated crop tool: click a node to auto-detect a color-boundary crop
region or drag to preselect one, previewed with an on-canvas draft overlay
before entering the crop editor. Route uploads through renderContent so the
transparent WebP texture feeds the fast display path. Add node --test
coverage for the leafer renderer and color-boundary detection.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
