v3.10.0

Added

• stringify(input: PGN | PGN[], options?: StringifyOptions): string — converts
  parsed PGN objects back to valid PGN strings (semantic round-trip fidelity).
  Accepts a single game or an array of games. Reconstructs SAN from Move
  fields, re-serializes annotation commands ([%cal], [%csl], [%clk],
  [%eval]) back into comment blocks, and preserves RAVs and NAGs. Fires
  onWarning for recoverable issues (invalid castling destination, negative
  clock).

Changed

• src/index.ts refactored into focused internal modules (src/types.ts,
  src/parse.ts, src/stream.ts, src/stringify.ts). Public API unchanged.

Fixed

• Tagless games with no moves (e.g. [Result "*"]\n\n*) now parse correctly.
  Previously the grammar required at least one move in the movetext.