Incorporate automatic summarization into context window overflow handling

Extend the implementation to automatically trigger summarization when Bedrock's context window limits are exceeded. This involves error detection for specific Bedrock error messages, fallback mechanisms, and updating the conversation handling logic to recover gracefully from overflow errors. The goal is to make the transition seamless when token limits are reached.

首先跟踪对话处理逻辑，以及处理 Bedrock 上下文窗口错误消息的路径；payload 没有指定具体的文件或测试。定义所需的溢出检测和回退行为，然后验证在超出 token 限制时对话能够无缝恢复。

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