feat(commands): add /seo-auditor — 7-phase SEO audit pipeline for documentation
- 7 phases: discovery → meta tags → content quality → keywords → links → sitemap → report
- Integrates 8 marketing-skill scripts: seo_checker, content_scorer,
humanizer_scorer, headline_scorer, seo_optimizer, sitemap_analyzer,
schema_validator, topic_cluster_mapper
- References 6 SEO knowledge bases for audit framework, AI search,
content optimization, URL design, internal linking, AI detection
- Auto-fixes: generic titles, missing descriptions, broken links, orphan pages
- Preserves high-ranking pages — only fixes critical issues on those
- Registered in both commands/ (distributable) and .claude/commands/ (local)
Also: sync all doc counts — 28 plugins, 26 eng-core skills, 21 commands
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>