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
• carry a provenance-pinned PHP 8.3 runtime overlay rebuilt on 3.1.52 with the mysqli_poll timeout fix from Fix mysqli_poll timeouts in PHP-WASM WordPress/wordpress-playground#4170
• 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

Why both overlays are carried

Both upstream fixes are required, and neither is available in a released package:

Upstream	Provides	Status
WordPress/wordpress-playground#4108	external extension ABI	merged 2026-08-31, unreleased — 3.1.52 was published ~7h earlier
WordPress/wordpress-playground#4170	mysqli_poll timeout fix	open

A carried overlay must be paired with the driver it runs under. Bumping the driver to 3.1.52 while leaving the PHP 8.3 overlay built against 3.1.46 produced a version skew that hung inside zif_mysqli_poll until the recipe timed out. The 8.3 overlay is therefore rebuilt from #4170 against 3.1.52, for both asyncify and jspi, so whichever mode the runtime selects carries the fix.

Both overlays record their upstream revision, source package, and tree digest in runtime-overlays/, and both become deletable as soon as their upstream change ships.

Verified

• tests/mysqli-poll.integration.test.ts passes against the rebuilt 8.3 overlay (PHP 8.3.33, MariaDB)
• 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

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.

Known limitation

The jspi runtime is carried and rebuilt but not directly exercised: JSPI feature detection reports unavailable on the Node versions used here, so asyncify is the mode under test. Carrying both avoids a silent hang if selection changes.

AI assistance

OpenAI GPT-5.6 Sol via OpenCode traced the PHP.wasm ABI mismatch, diagnosed the driver/overlay version skew behind the mysqli_poll timeout, rebuilt both PHP 8.3 runtimes from the upstream fix, assembled the provenance-bound overlays, and implemented the packaging and regression coverage. Reviewed by Chris Huber.