v0.1.0 of chess_on_dart

A high-performance, zero-allocation bitboard chess engine in Dart. Supports standard chess, Chess960, King of the Hill, Three-Check variants, FEN/PGN import/export, and SAN/UCI move formats. Changelog excerpt: - Initial release of high-performance, zero-allocation chess engine for Dart. - Supports Standard Chess, Chess960, King of the Hill, and Three-Check. - High-performance bitboards, Magic Bitboards, FEN, PGN, SAN, and UCI support.