Add review-gated publishing automation

[luyx-66]

Summary

• monitor the APIMART /v1/models catalog each Wednesday and open a draft PR only when public model identifiers change
• move scheduled guide publication from direct main commits to review-gated draft PRs
• keep GitHub Pages deployment restricted to main
• add mock-based catalog normalization coverage to the quality workflow

Safety

• model-catalog checks are read-only and do not incur generation cost
• credentials remain in GitHub Actions secrets and are never written to artifacts
• queued content still passes uniqueness, evidence, SEO, and disclosure validation before a PR is created

Validation

• npm test (50 guides, 12 scheduled guides, 10 measured comparisons, 50 fixtures; build and rendered tests passed)
• model snapshot normalizer: first run detected change, second identical run remained stable
• all workflow YAML parsed successfully
• git diff --check