getsentry/publish Yarn Classic tooling

Use Volta-pinned Yarn Classic 1.22.22 for getsentry/publish: yarn install, yarn test, yarn lint, and yarn prettier; never use pnpm or npm. Chose Yarn over the repository-wide pnpm habit because Publish has yarn.lock and CI installs/tests with Yarn; another package manager creates unrelated resolution churn. In particular, do not commit pnpm-lock.yaml. Source is CommonJS; tests are Vitest ES modules under matching __tests__/ paths.