fix: overlay PHP-WASM mysqli polling

[chubes4]

Summary

• carry a temporary, checksum-pinned PHP 8.3.32 Node WASM package built from WordPress Playground PR #4170
• resolve @php-wasm/node-8-3 to the vendored package with source, patch, artifact, and binary provenance
• verify the real InnoDB lock-wait mysqli_poll() timeout against MariaDB in the standard contract workflow
• retain a manual rebuild workflow so the overlay can be reproduced and removed after Playground publishes the fix

Closes #2010.

Verification

• Full Agent Task Contracts: https://github.com/Automattic/wp-codebox/actions/runs/31975512331
• The focused test:mysqli-poll-integration completed successfully inside that run.
• Build artifact source run: https://github.com/Automattic/wp-codebox/actions/runs/31974044661
• Local: clean npm ci, npm run build, actionlint, release-package content assertion, artifact SHA-256 verification, and git diff --check

Temporary Overlay

The package is pinned to Playground source 581c7c172428159eb4e6c5309054a568cd39a97a, patch commit d746c930477eae3d726f754753eb92692ad30855, and artifact SHA-256 109c079c958e1ab35ebcd098bdd895b080e2c5405b147f93ecb04e768c723553. Remove the package, lockfile override, rebuild workflow, and regression-specific overlay documentation after a published Playground package contains the same fix.

AI Assistance

OpenAI gpt-5.6-sol via OpenCode was used to inspect the runtime/build contracts, implement the temporary overlay and regression, and execute verification. Chris Huber reviewed and owns the changes.