Extract WordPress command runners

[chubes4]

Summary

• Extract WordPress command implementations into wordpress-command-runners.ts.
• Move run-php, Plugin/Theme Check, abilities, bench, PHPUnit, and Core PHPUnit orchestration out of index.ts.
• Keep index.ts responsible for runtime bootstrapping, command routing callbacks, artifact lists, and WP-CLI bridge wiring.

Testing

• npm run build
• npm run plugin-check-normalization-smoke
• npm run theme-check-normalization-smoke
• npm run phpunit-diagnostic-artifact-smoke
• npm run core-phpunit-command-smoke
• npm run recipe-bench-smoke
• npm run runtime-action-adapter-smoke
• npm run ability-login-blueprint-smoke
• npm run command-registry-smoke
• npm run package-distribution-smoke

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Drafted the WordPress command runner extraction, ran verification, and prepared the PR summary for Chris to review.