docs: Add v3.9.1 marketing campaign - Security & Level 5 Empathy

Comprehensive marketing campaign for v3.9.1 release featuring:
- Security hardening story (174 tests, Pattern 6, +1143%)
- Level 5 empathy implementation (teaching AI coding standards)
- Ready-to-post content for Reddit, Twitter, Dev.to, HN
- Framework background for new audiences
- Launch timeline and success metrics

Content includes:
1. Hero story: From fixing bugs to preventing entire bug classes
2. Reddit post for r/ClaudeAI (with framework intro)
3. Twitter thread (7 tweets)
4. Dev.to article outline
5. Hacker News Show HN post
6. FAQ responses pre-prepared
7. Visual asset requirements
8. Engagement strategy

Theme: 'Teaching AI to prevent security bugs by default'
Hook: 'We just did something meta: taught Claude to never write insecure code'
Data: 80h/month saved, -62% standards violations, 0 security issues

Launch timeline:
- Jan 8: r/ClaudeAI (soft launch)
- Jan 9: Twitter + r/Python
- Jan 10: Dev.to + LinkedIn
- Jan 15-16: Hacker News (Show HN)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: silversurfer562