实现 Issue #299: README 文件中的License写错了 (#300)

* Initial plan for Issue #299: README 文件中的License写错了

* docs: fix incorrect license information in README

Corrected license references from MIT to Apache License 2.0 to match
the actual LICENSE file. Updated both the license badge and license
section text for consistency.

Closes #299

---------

Co-authored-by: qiniu-ci <qiniu-ci@qiniu.com>

Author: qiniu-ci

README.md

@@ -2,7 +2,7 @@
 
 [![Go Report Card](https://goreportcard.com/badge/github.com/qiniu/codeagent)](https://goreportcard.com/report/github.com/qiniu/codeagent)
 [![Go Version](https://img.shields.io/github/go-mod/go-version/qiniu/codeagent)](https://go.dev/)
-[![License](https://img.shields.io/badge/License-MIT-blue.svg)](LICENSE)
+[![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](LICENSE)
 [![CI](https://github.com/qiniu/codeagent/workflows/CI/badge.svg)](https://github.com/qiniu/codeagent/actions)
 
 **CodeAgent** is a Go-based AI-powered automated code generation and collaboration system that seamlessly integrates with GitHub. It receives AI instructions through GitHub webhooks and automatically handles code generation, modification, and review tasks for Issues and Pull Requests.
@@ -290,7 +290,7 @@ Please read our [Contributing Guide](CONTRIBUTING.md) for detailed information a
 
 ## 📄 License
 
-This project is licensed under the [MIT License](LICENSE).
+This project is licensed under the [Apache License 2.0](LICENSE).
 
 ## 🙏 Acknowledgments