Publish GPT-5.6 OpenAI Docs skill

[kkahadze-oai]

Summary

Publishes the OpenAI Docs skill in the OpenAI Developers plugin with GPT-5.6-ready model routing, prompting guidance, and migration guidance.

• resolves latest/current/default-model requests through the machine-readable latest-model.md contract
• fetches the exact prompting and migration URLs returned by the live docs
• preserves explicitly named GPT-5 model targets
• adds bundled GPT-5.6 Sol, Terra, and Luna migration judgment
• adds a CommonJS-safe resolver and self-starting executable wrapper
• bumps the plugin to 1.3.0 so the new skill is published
• updates the existing OpenAI Developers test to validate the bundled skill directly

Developer impact

Codex can answer current OpenAI docs questions and migrate projects to GPT-5.6 using the canonical live docs contract, with bundled fallback guidance when needed.

Validation

• skill validator: passed
• OpenAI Developers tests: 29 passed, 1 unrelated monorepo-only skip, 0 failed
• live resolver smoke test returned gpt-5.6-sol and both standalone guide URLs
• CommonJS syntax check: passed
• plugin and marketplace JSON parsing: passed
• git diff --check: passed
• migration eval: 30/30 passed, 0 critical failures
• latest-model/prompting routing eval: 33/33 passed, 0 critical failures