gpu.js is only needed for the types index.d.ts imports — the runtime
mock requires nothing at all. Declared as a hard peer dependency, npm 7+
installs a published copy of gpu.js alongside this package, including
into gpu.js's own dependency tree, where it is circular and pulls in a
second copy of gpu.js's dependencies.

peerDependenciesMeta.optional keeps the declaration honest for
TypeScript consumers while telling npm not to install or warn about it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>