Fix PHP 8.4 external extension ABI

[chubes4]

Closes #2474.

Summary

• carry a provenance-pinned PHP 8.4 runtime overlay containing the external-extension ABI fix from Fix external PHP extension ABI exports WordPress/wordpress-playground#4108
• converge the Node Playground packages on 3.1.52
• materialize both pinned overlays into the CLI and WordPress plugin release artifacts
• add deterministic ABI export and release-consumer coverage

Status: blocked, do not merge

CI is red on tests/mysqli-poll.integration.test.ts and that failure is real, not flaky.

Bumping the Playground driver stack to 3.1.52 skews it against the PHP 8.3 overlay, whose binaries are built from 3.1.46 plus an unreleased php_wasm.c mysqli_poll patch. A 3.1.52 driver against 3.1.46-patched WASM hangs inside zif_mysqli_poll and the recipe times out after 180s.

The 8.3 overlay in this branch is byte-identical to main; the skew comes from the driver bump alone.

Upstream dependencies

Upstream	Provides	Status
WordPress/wordpress-playground#4108	external extension ABI	merged 2026-08-31, not yet released — 3.1.52 was published ~7h earlier
WordPress/wordpress-playground#4170	mysqli_poll timeout fix	open
WordPress/wordpress-playground#4146	clean PHP worker processes	open

#4108 is expected in the next weekly release (~3.1.53), at which point this overlay can be deleted outright.

Resolving the red requires one of:

1. #4170 lands and ships, removing the need for a patched 8.3 overlay entirely (preferred — the fix lives in shared php_wasm.c, so a release rebuilds every version and mode)
2. the 8.3 overlay is rebuilt against 3.1.52 with the patch reapplied, which needs both asyncify and jspi build output
3. this PR drops the driver bump and ships only the 8.4 ABI overlay

Verified

• npm run test:php-wasm-external-extension-abi
• npm run test:php-wasm-runtime-rejection-any-command
• npm run test:phpunit-runtime-rejection
• npm run test:release-package-coverage
• npm run build, npx patch-package --check, git diff --check

The ABI overlay itself is proven: a PHP 8.4 JSPI extension workload that previously failed at startup with an unnamed TypeError: resolved is not a function now boots PHP 8.4.25, loads its extension, and reaches command dispatch.

AI assistance

OpenAI GPT-5.6 Sol via OpenCode traced the PHP.wasm ABI mismatch, assembled the provenance-bound overlay, implemented the packaging and regression coverage, diagnosed the mysqli_poll CI failure, and drafted this description. Reviewed by Chris Huber.