Add a bookmark feature in CLI to jump back and forth

### Describe the feature or problem you'd like to solve

I am having a conversation back and forth with agency and it has provided some feedback 1, 2, 3, 4... I am working on 1 and lot of back and forth has happened. Now I want to go back up to the same place where number 2 or 3 is. But that involves a lot of scrolling. When I ask agency to refresh my memory on 2 or 3, the text it returns is completely different than before.

### Proposed solution

A bookmark feature would allow me to jump back and forth between the work I am doing with the agency and collaborating with it. Think of it as a parking lot in meetings where you park a list of ideas and go back to it one by one.

### Example prompts or workflows

_No response_

### Additional context

_No response_

该 issue 未指出文件、入口点或测试。首先定位 CLI 的对话输入和导航处理，然后定义书签的创建、列出和重新访问方式；完成的标准应是用户能够在保存的对话位置之间可靠地跳转而不会丢失上下文。

由索引模型根据 Issue 内容生成。