Declare developer docs bootstrap contract

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Summary

• Pins the developer docs workflow to a Docs Agent revision that supports bootstrap contracts.
• Declares the required Build with WordPress developer docs bootstrap surface: README entry point, docs index, architecture, generated outputs, skills/integrations, and contributor workflows.
• Adds contract checks for required docs files, docs page count, entry point links, and deferred/backlog phrase avoidance.

Verification

• actionlint .github/workflows/developer-docs-agent.yml

Related

• Closes Declare full developer-docs bootstrap output contract #63.
• Depends on Enforce Data Machine agent workspace contract checks Extra-Chill/homeboy-extensions#1315.
• Depends on Expose docs bootstrap contracts docs-agent#92 and Pass workspace contract checks to runner docs-agent#93.

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Updated the workflow contract wiring and verified syntax for human review.