PHPUnit workload fails parsing bundled Util/Test.php

## Problem

A WordPress PHPUnit workload fails before repository test discovery because the bundled PHPUnit source cannot be parsed.

## Reproduction

From a Data Machine Code worktree, run:

`homeboy review test data-machine-events --path /var/lib/datamachine/workspace/data-machine-events@fix-486-event-index-integrity --placement local`

Focused and unfiltered runs fail identically.

## Error

`ParseError: Unclosed '{' on line 154 at /tmp/wp-codebox-inputs/0-wp-codebox-vendor-73845ca47d2f/phpunit/phpunit/src/Util/Test.php:155`

The repository's modified PHP files pass `php -l`, and the failure points to the WP Codebox-provided PHPUnit vendor payload before any project test executes.

## Runtime

- wp-codebox-workspace: 0.12.14
- @automattic/wp-codebox-core: 0.12.14
- @automattic/wp-codebox-playground: 0.12.14
- WordPress: latest

Reproduce with the documented homeboy review command and inspect the bundled PHPUnit file at /tmp/wp-codebox-inputs/0-wp-codebox-vendor-73845ca47d2f/phpunit/phpunit/src/Util/Test.php, especially around lines 154-155. Compare the WP Codebox-provided PHPUnit payload with the runtime versions listed in the issue; done means PHPUnit parses successfully and repository test discovery proceeds.

Written by the indexing model from the issue text.