Minimum Moves to Move a Box to Their Target Location

Given a grid with one player S, one box B, and one target T, find the minimum number of pushes (player moving into the box to move it one cell) to get B to T, where the player can walk on empty cells but cannot pass through the box. This is a shortest-path search in the state space of (box position, player position), requiring checks of player reachability to valid push positions; return -1 if unreachable.