Upgrade Playground runtime for complete external-extension ABI

## Problem

WP Codebox pins WordPress Playground `3.1.46`. A PHP 8.4 JSPI extension produced through the supported `@php-wasm/compile-extension` workflow can import public PHP symbols that this main module does not export. Runtime boot then fails before command dispatch with:

```text
TypeError: resolved is not a function
cause: Comlink method call failed
```

Static `WebAssembly.Module.imports()` comparison against `@php-wasm/node-8-4@3.1.46` confirms missing function exports including:

```text
explicit_bzero
convert_to_null
_emalloc_448
php_password_algo_find
php_password_algo_register
sscanf
```

WordPress Playground fixed this contract in [issue #4107](https://github.com/WordPress/wordpress-playground/issues/4107) and merged [PR #4108](https://github.com/WordPress/wordpress-playground/pull/4108). The current npm release is `3.1.52`; WP Codebox still pins `3.1.46`.

## Expected

- Converge all Playground/PHP.wasm packages on a release containing the complete external-extension ABI.
- Add deterministic coverage comparing a fixture extension's function imports with the selected main-module exports so dependency drift fails before runtime execution.
- Verify a JSPI external extension reaches PHP command dispatch instead of surfacing the unnamed dynamic-linker TypeError.

## Evidence

A retained WP Codebox recipe run proved backend package import, runtime creation, managed MariaDB readiness, and extension-manifest resolution. The failure occurred when PHP.wasm first booted; the workflow command was never recorded. The package provenance was WP Codebox `0.26.3`, Playground CLI/PHP.wasm `3.1.46`, PHP `8.4`, JSPI.

## AI assistance

OpenAI GPT-5.6 Sol via OpenCode traced the runtime artifact to PHP.wasm's dynamic linker, compared side-module imports with main-module exports, found the merged upstream ABI repair, and drafted this tracker with Chris Huber.

Start with the Playground/PHP.wasm package manifests, the @php-wasm/node-8-4 runtime, and the @php-wasm/compile-extension workflow. Use WebAssembly.Module.imports() to compare the fixture extension's imports with the selected main-module exports, then run the retained WP Codebox recipe. Done means the ABI comparison is deterministic and a JSPI extension reaches PHP command dispatch without the dynamic-linker TypeError.

Written by the indexing model from the issue text.