docs: Add comprehensive marketing plan for v3.6.0 launch

Created complete marketing push documentation:

1. MARKETING_PLAN_v3.6.0.md
   - Multi-channel strategy (Reddit, HN, Twitter, LinkedIn, Dev.to)
   - Timeline and content calendar
   - Success metrics and analytics setup
   - Risk mitigation and emergency protocols
   - Community engagement strategy

2. SOCIAL_MEDIA_POSTS.md
   - Copy-paste ready content for all platforms
   - Twitter thread (7 tweets)
   - Reddit posts (r/Python, r/MachineLearning, r/programming, r/learnprogramming)
   - LinkedIn professional post
   - Hacker News Show HN post
   - Dev.to teaser
   - GitHub release notes
   - Email newsletter template

3. BLOG_POST_v3.6.0.md
   - 8-minute long-form article
   - Technical deep dive on error message improvements
   - Use cases and examples
   - Installation tiers explanation
   - Roadmap and community section

4. LAUNCH_CHECKLIST.md
   - Hour-by-hour execution guide
   - Pre-launch verification steps
   - Platform-specific posting instructions
   - Metrics tracking checklist
   - Week 1 content calendar

Ready for review and execution tomorrow.

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

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Author: 2 people