Refactor LayerTree: Atlaskit DnD, split LayerRow, shared icons
Replace manual pointer-capture drag with @atlaskit/pragmatic-drag-and-drop:
- Tree-aware hitbox (reorder-above, reorder-below, make-child)
- Native drag preview via Atlaskit adapter
- No more manual DOM measurement for drop zones
Split into focused files:
- LayerTree.vue (164 lines) — tree data, expand, selection
- LayerRow.vue (175 lines) — per-row: icon, rename, lock/visibility, DnD setup
- utils/layer-icons.ts (43 lines) — icon maps shared across components
- use-layer-drag.ts (127 lines) — Atlaskit DnD composable in SDK
Add toggleNodeVisibility/toggleNodeLock per-node methods to editor.
492d9dfa75