Add WordPress recipe build CLI command

[chubes4]

Summary

• Adds wp-codebox recipe build phpunit --options <path> [--output <path>] so external shell runners can use the exported WordPress PHPUnit recipe builder without importing TypeScript packages directly.
• Reuses buildWordPressPhpunitRecipe() from runtime-core and covers the command with a focused CLI smoke.
• Extracts the CLI entry router for direct smoke execution without spawning a subprocess.

Verification

• npm run build
• npm run recipe-build-cli-smoke

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (openai/gpt-5.5)
• Used for: Drafted the CLI wrapper, smoke coverage, verification runs, and PR description. Chris remains responsible for review and merge.