Restructure skill numbering: SEO 11-30, GTM 60-69, reserve 19-28 for future skills

Renumber 12 existing skills to new ranges:
- SEO: 11→13, 12→18, 13→16, 14→17, 15→14, 16→15, 17→29, 18→30, 19→12
- GTM: 20→60, 21→61, 22→62

Update cross-references in gateway architect/builder skills, GTM guardian
README, CLAUDE.md (skill tables + directory layout), and AGENTS.md
(domain routing ranges).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

AGENTS.md

@@ -115,13 +115,15 @@ Task 2: general-purpose - "Implement the planned skill"  # Needs Task 1 result
 
 ## Domain-Specific Routing
 
-### SEO Skills (10-19)
+### SEO Skills (11-30)
 
 - Use **seo-advisor** agent for SEO strategy questions
 - Use **Explore** to understand existing SEO script patterns
 - Python scripts in these skills follow `base_client.py` patterns
+- `11-seo-comprehensive-audit` orchestrates skills 12-18 for unified audits
+- Skills 19-28 are reserved for future SEO capabilities
 
-### GTM Skills (20-29)
+### GTM Skills (60-69)
 
 - Use **gtm-manager** agent for GTM-specific debugging
 - Requires Chrome GTM Debug profile for live testing