fix: harden emnapi v2 memory, threads, and WASI packaging

[Brooooooklyn]

Summary

Harden emnapi v2 for production WASI consumers discovered while validating napi-rs and Rolldown.

This remains v2-only. It does not add or test a v1 fallback.

Runtime fixes

• Refresh detached or stale WebAssembly memory views after growth, reentrant JavaScript calls, and cross-agent shared-memory growth.
• Preserve wasm32 high addresses and wasm64 pointer/size semantics without unsafe Number truncation.
• Harden TSFN delivery, retries, queue reclamation, worker-loss recovery, and bounded-queue shutdown.
• Make async-work worker initialization, failure, termination, and generation ownership deterministic.
• Confirm worker termination before retiring ownership and handle memory64 thread-spawn payloads.
• Make context keepalive independent of MessageChannel, add configurable autoDestroy, and dispose host handles/listeners deterministically.
• Make cleanup-hook mutation safe while cleanup is draining.

WASI npm package

The published emnapi v2 archive now carries and validates this exact matrix:

wasm32-wasip1:
  libemnapi.a
  libemnapi-basic.a
  libemnapi-basic-mt.a

wasm32-wasip1-threads:
  libemnapi.a
  libemnapi-basic.a
  libemnapi-basic-mt.a
  libemnapi-basic-napi-rs-mt.a
  libemnapi-mt.a
  libemnapi-napi-rs-mt.a

Release validation now:

• removes stale target/install directories before packaging;
• enforces a global WASI archive allowlist;
• verifies archive symbol profiles with llvm-nm;
• verifies napi-rs archives are not copies of regular archives;
• installs the packed tarball into a clean consumer;
• links real threadless and threaded smoke modules from the installed package;
• supports Ninja, mingw32-make, and nmake, including Windows .cmd/.bat spawning.

The real consumer link profiles are:

• wasm32-wasip1: libemnapi-basic.a
• wasm32-wasip1-threads: libemnapi-basic-napi-rs-mt.a

Status

• Based on toyobayashi/emnapi@44ae05d.
• Draft head: 1c5ee42be87843adcd4a410729eea37ee8a7df79.
• Tracking context: infra: attempt to remove tokio rolldown/rolldown#9464.

Verification

Passed locally on July 10, 2026 with Node 26.4.0:

• packed-package build/install/symbol/link validation with WASI SDK 32.0;
• packed-package build/install/symbol/link validation with WASI SDK 33.0;
• rebuilt WASI-thread fixtures with WASI SDK 33.0;
• repeated the regular and typed bounded nonblocking TSFN saturation regressions 10/10 each;
• changed-script syntax checks and ESLint;
• git diff --check.

All six GitHub CI targets pass at the exact draft head. The final CI-only change prevents JavaScript from draining the bounded TSFN queue before native code observes napi_queue_full.

Earlier runtime validation on this branch also passed the focused Context, memory-growth, TSFN, async-work recovery, worker-termination, wasm64, and WASI-thread suites. The full WASI-thread run reaches the independently reproduced pre-existing async_context/gcable.test.js failure under Node 26.4.0.