Leetcode 1485. Clone Binary Tree With Random Pointer

Given a binary tree where each node has left, right, and an extra random pointer to any node (or null), produce a deep copy of the tree so the cloned nodes replicate the original tree's left/right structure and random relationships. This requires traversing the tree and mapping original nodes to their clones (e.g., via a hash map or an in-place interleaving trick) to correctly assign random pointers.