Add community documentation entry points

[Copilot]

The repository had strong product docs but no community-facing entry points for contribution, conduct, security, or support. This adds the minimal open-source community surface needed for a mature project and links it from the main README in both languages.

• Community docs

  • Add CONTRIBUTING.md with contribution expectations and local development commands
  • Add CODE_OF_CONDUCT.md with participation and enforcement guidance
  • Add SECURITY.md with private vulnerability reporting guidance
  • Add SUPPORT.md with where to ask questions and report issues

• README integration

  • Add a dedicated Community section to README.md
  • Add a mirrored 社区 section to README_CN.md
  • Keep links pointed at repository-local docs for easy discovery

## Community

- [Contributing Guide](.github/CONTRIBUTING.md)
- [Code of Conduct](.github/CODE_OF_CONDUCT.md)
- [Security Policy](.github/SECURITY.md)
- [Support](.github/SUPPORT.md)

Original prompt

/deep-dive 我现在在构建完成的社区文档，让这个项目作为成熟的开源社区项目

Created from VS Code.