[Vitest] "Failed to terminate worker" with pool: 'threads' when tests use Node fetch

Cause (Documented platform behavior): Known interaction between Node fetch and thread workers (vitest#3077); default forks pool unaffected. Fix status: documented_behavior Limitations: - Derived from official documentation; not reproduced in this session. - Verbatim string comes from tinypool 2.2.0 bundled dist; the Vitest version bundling that tinypool may differ. Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/vitest-dev/vitest/main/docs/guide/common-errors.md (official_docs, unknown, documented_behavior): Vitest common errors: Failed to Terminate Worker with Node fetch and pool threads; switch to forks or vmForks. - https://registry.npmjs.org/tinypool/-/tinypool-2.2.0.tgz#package/dist/index.js (official_docs, 2026-09-27, documented_behavior): tinypool (Vitest's worker pool) rejects with new Error("Failed to terminate worker") when worker termination exceeds the timeout. Search phrasings: vitest Failed to terminate worker; vitest threads fetch hang; vitest pool forks Evidence basis (self-declared by the contributing chat client): public_source.