Pin Homeboy test runner release

[chubes4]

Summary

• Pin the Homeboy GitHub Action to 0.222.4 so the test workflow uses the fixed WP Codebox integration instead of the historical 0.218.0 toolchain that failed before producing PHPUnit counts.
• Keeps the product code and test suite unchanged; this only stabilizes the CI runner used by .github/workflows/test.yml.

Verification

• homeboy test --json-summary
• Result: 27 passed, 0 failed, 0 skipped; 360 assertions via WP Codebox/PHPUnit.

Fixes #119.

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Investigated the Homeboy CI failure, reproduced the current test command locally, identified the stale runner/toolchain failure mode, and drafted the workflow pin. Chris remains responsible for review and merge.