// Chess vs MCTS, built on Meep.
//
// Player is Black (sits at +Z, camera side). White is an MCTS opponent that
// runs as a Task on engine.executor so the page never blocks. Selection,
// move-validation, MCTS expansion, and game-over detection all share the
// same rules engine defined below.
//
// No castling, no en passant, no pawn promotion - keeps the rules code
// compact and the MCTS state cheap to clone. End-game banner fires on
// checkmate only.

// ENV-HDR-MARKER: this build has the HDR background + environment hook wired
// at the engine-bootstrap section.
