Sum of Nodes at a Specific Depth in a Binary Tree

You are given the root of a binary tree and an integer depth.

Your task is to compute the sum of all node values located at the specified depth.

Note that:

• The root node is defined to be at depth 0.
• The depth of a node increases by 1 for each level down from its parent.

Return the total sum of node values at the given depth. If no nodes are found at the specified depth, return 0.