feat: add polished blog article on scaling code intelligence

- Added comprehensive blog post about scaling from 1,000 to 1,000,000 files
- Covers real-world challenges and solutions in production
- Documents memory management, dependency scanning, and architecture decisions
- Includes actual code examples and performance insights from our journey
- Added missing tags: scalability, memory-management, dependency-scanning
- Fixed MDX compilation issue with HashMap references

Author: milliondreams