Generate public documentation reference contract

[muxx]

Summary

• generate filtered public control-plane, envd, Process, and Filesystem references
• generate grouped JavaScript, Python, and CLI Markdown from source
• publish a hashed manifest consumed by the documentation site
• update SDK documentation links to the new reference routes

Verification

• pnpm format:check
• pnpm lint
• pnpm typecheck
• pnpm test
• pnpm check:generated