feat: Implement comprehensive AI-era SEO optimizations

- Add llms.txt file for AI crawlers (llmstxt.org standard)
- Enhance robots.txt with 15+ AI bot rules (GPTBot, ClaudeBot, etc.)
- Expand JSON-LD structured data from 1 to 12+ schema blocks:
  - Person (enhanced with occupations, languages, employers)
  - WebSite, BreadcrumbList, ProfilePage
  - EducationalOccupationalCredential (dynamic per education)
  - Course (dynamic per certification)
- Create doc/15-SEO.md with comprehensive SEO documentation
- Update MODERN-WEB-TECHNIQUES.md with SEO section (techniques 11-13)

Based on WPBeginner 2025 SEO recommendations for AI Overviews,
structured data, and E-E-A-T signals.

static/robots.txt

@@ -1,22 +1,29 @@
 # robots.txt for juan.andres.morenorub.io
+# Last Updated: 2025-11-30
 
-# Allow all search engines
+# =============================================================================
+# DEFAULT RULES - Allow all search engines
+# =============================================================================
 User-agent: *
 Allow: /
 
-# Disallow admin/internal paths (if any in future)
+# Disallow admin/internal paths
 Disallow: /admin/
 Disallow: /api/internal/
 Disallow: /.git/
 Disallow: /.env
 
-# Sitemap location
+# =============================================================================
+# SITEMAPS & AI CONTENT
+# =============================================================================
 Sitemap: https://juan.andres.morenorub.io/static/sitemap.xml
 
-# Crawl-delay (optional, helps prevent server overload)
-# Crawl-delay: 1
+# LLMs.txt for AI crawlers (standard: https://llmstxt.org/)
+# Location: https://juan.andres.morenorub.io/static/llms.txt
 
-# Allow specific search engines (explicit)
+# =============================================================================
+# TRADITIONAL SEARCH ENGINES
+# =============================================================================
 User-agent: Googlebot
 Allow: /
 
@@ -34,3 +41,76 @@ Allow: /
 
 User-agent: YandexBot
 Allow: /
+
+# =============================================================================
+# AI CRAWLERS & LLM BOTS - Explicitly allowed
+# =============================================================================
+
+# OpenAI - ChatGPT, GPT-4
+User-agent: GPTBot
+Allow: /
+
+User-agent: ChatGPT-User
+Allow: /
+
+# Anthropic - Claude
+User-agent: ClaudeBot
+Allow: /
+
+User-agent: Claude-Web
+Allow: /
+
+User-agent: anthropic-ai
+Allow: /
+
+# Google AI - Bard, Gemini
+User-agent: Google-Extended
+Allow: /
+
+# Meta AI
+User-agent: FacebookBot
+Allow: /
+
+User-agent: Meta-ExternalAgent
+Allow: /
+
+User-agent: meta-externalagent
+Allow: /
+
+# Perplexity AI
+User-agent: PerplexityBot
+Allow: /
+
+# Cohere AI
+User-agent: cohere-ai
+Allow: /
+
+# Common Crawl (used by many AI models)
+User-agent: CCBot
+Allow: /
+
+# Amazon/Alexa
+User-agent: Amazonbot
+Allow: /
+
+# Apple - Applebot (for Siri, Spotlight)
+User-agent: Applebot
+Allow: /
+
+# Microsoft Copilot
+User-agent: Copilot
+Allow: /
+
+# You.com AI
+User-agent: YouBot
+Allow: /
+
+# Brave Search
+User-agent: BraveBot
+Allow: /
+
+# =============================================================================
+# CRAWL RATE LIMITS (Optional)
+# =============================================================================
+# Uncomment if needed to prevent server overload
+# Crawl-delay: 1