Add AGENTS.md

[yeahdongcn]

Prompt:

Generate an AGENTS.md file in the project root following the AGENTS.md specification and examples.
 
Use this repository as context and include sections that help an AI agent work effectively with this project, including:
- Project overview
- Build and test commands
- Code style guidelines
- Testing instructions
- Security considerations
 
Base the content on the actual structure, tooling, and conventions used in this repository.
Keep the file concise, practical, and actionable for an AI agent contributing to the project.