Add Data Machine bundle task execution

[chubes4]

Summary

• Forward datamachine_bundle through wp-codebox agent-task-run into sandbox recipe steps.
• Execute bundle tasks inside the sandbox through the canonical datamachine/run-agent-bundle ability when a bundle run request is present.
• Update WordPress plugin smoke coverage for the new contract and the current runtime plugin activation hook.

Testing

• npm run build
• npm run wordpress-plugin-smoke
• git diff --check

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Implemented the WP Codebox sandbox integration and focused smoke coverage; Chris remains responsible for review and merge.