sashite-epin 2.0.0

EPIN (Extended Piece Identifier Notation) extends PIN to provide style-aware piece representation in abstract strategy board games. This gem implements the EPIN Specification v1.0.0 with a modern Ruby interface featuring immutable identifier objects and functional programming principles. EPIN adds derivation markers to PIN that distinguish pieces by their style origin, enabling cross-style game scenarios and piece origin tracking. Represents all four Game Protocol piece attributes with full PIN backward compatibility. Perfect for game engines, cross-tradition tournaments, and hybrid board game environments.