Stockfish.js 18 browser runtime asset for Inchess.

This runtime component is distributed separately from the Inchess application
bundle under GPL-3.0. It is based on:

- Stockfish.js by Nathan Rugg
  https://github.com/nmrugg/stockfish.js
- Stockfish by the Stockfish developers
  https://github.com/official-stockfish/Stockfish

The JavaScript and WebAssembly assets in this directory were copied from the
npm package stockfish@18.0.7, using the lite single-threaded Stockfish 18 build:

- stockfish-18-lite-single.js
- stockfish-18-lite-single.wasm

The exact runtime package used by Inchess is published at:

https://github.com/msgridin/inchess-stockfish-runtime/releases/tag/stockfish-18.0.7-inchess.1

The Stockfish.js package README credits Chess.com, the Stockfish team, and
other Stockfish.js contributors. See SOURCE.txt and BUILD.md for the source
and rebuild pointers for this exact distributed runtime component.