sashite-pin 3.1.0

PIN (Piece Identifier Notation) provides a rule-agnostic format for identifying pieces in abstract strategy board games. This gem implements the PIN Specification v1.0.0 with a modern Ruby interface featuring immutable identifier objects and functional programming principles. PIN uses single ASCII letters with optional state modifiers and case-based side encoding (A-Z for first player, a-z for second player), enabling precise and portable identification of pieces across multiple games. Perfect for game engines, board game notation systems, and hybrid gaming platforms requiring compact, stateful piece representation.