Add CLAUDE.md file for AI agent development guidelines

[suxiaogang223]

Many modern Rust projects are adopting AI-assisted development tools (like Claude, GitHub Copilot, etc.) to improve developer productivity. To help these AI agents better understand project structure, coding standards, and development workflows, some projects have created dedicated guideline files.

Reference: The Vortex project has implemented a similar approach with their CLAUDE.md file, which serves as a good example of how such guidelines can be structured.

These files serve as a structured knowledge base that helps AI tools:

• Understand project architecture and module organization
• Follow consistent coding style and patterns
• Know where to place tests and how to structure them
• Understand domain-specific concepts (ORC format, Arrow integration, etc.)

[suxiaogang223]

Another example https://github.com/lance-format/lance/blob/main/AGENTS.md