Build the strongest chess engine in 4 KB of Python

@rimuru2212

v4 engine: null-move pruning + PVS + LMR + history ordering, pawn-structure/rook-file/king-shield eval, QS delta pruning (50k nodes/move); local gauntlet 1654/1545 Elo vs 1451/1364 for v1, Sent through the API