Add blog post: MongoDB Vector Search for Semantic Applications

Comprehensive tutorial covering MongoDB Atlas Vector Search capabilities including:
- Semantic similarity search and RAG applications
- Vector indexing strategies and optimization
- SQL-style vector operations with QueryLeaf integration
- Multi-modal search, personalization, and performance tuning
- Practical examples for AI-powered search experiences

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

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

Author: rathboma