The rules are data in rules.ts; the engine plays custodial capture, the
king's own capture rule on and beside the throne, corner and edge
escape, shieldwalls, edge forts, encirclement, repetition and stalemate;
twenty tests pin them and play a bot game to a verdict on both boards.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jm2auWk6RP71CjaAb4FMoG