[Feature] 添加OpenAI API 格式的channel支持

[j4ckzh0u]

🎯 The Goal / Use Case

为将Picoclaw嵌入到已有的工程中，需要提供一个OpenAI API格式的channel，已有系统不做大的修改，即可调用Picoclaw的能力

💡 Proposed Solution

增加一个channel，能够配置openAI API的端口和api key

🛠 Potential Implementation (Optional)

🚦 Impact & Roadmap Alignment

• This is a Core Feature
• This is a Nice-to-Have / Enhancement
• This aligns with the current Roadmap

🔄 Alternatives Considered

💬 Additional Context

[corevibe555]

@alexhoshina I'd love to contribute on this. I have a commit ready for this change. If it’s okay with you, I can go ahead and open the PR.