Find Leaves of Binary Tree

You are given the `root` of a binary tree. Repeatedly remove all **leaf nodes** (nodes with no children) from the tree, and collect the values of these nodes in a list for each round of removal. Continue this process until the tree is empty. Return a _list of lists_, where each inner list contains the values of the leaves removed at each round, in the order they were removed. Constraints: - The number of nodes in the tree is in the range `[1, 100]`. - Each node's value is a unique integer. Return the _list of lists_ of node values, where each inner list represents the leaves removed in each round.