Craft.js duplicate (ContextMenu + keyboard shortcut) and paste were reusing
the original node's toNodeTree() output verbatim, so addNodeTree() inserted
duplicate node ids into the editor tree. Added regenerateTreeIds() which
deep-clones a NodeTree and remaps rootNodeId, node map keys, node.id,
internal node.data.parent, node.data.nodes, and node.data.linkedNodes via
Craft.js's own getRandomId(). Also fixed pasteNode to insert as a sibling
of the right-clicked node (using its parent) instead of using a leaf node
as the new parent, which previously threw.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
