Grouping customisation for chat sessions

It would be beneficial to introduce a custom organisation/tagging for the sessions in the app.

A possible idea to implement this would be to add the option to add the session to a specific group in the contextual menu for the session, or add a tag to the session and introduce a grouping based on tags.

首先查看会话 UI 及其上下文菜单，issue 将它们标识为可能的入口点。明确该 feature 应使用分组、标签，还是两者兼用，然后定义用户如何分配会话以及查看分组后的会话；完成标准应包括用于会话组织的清晰交互和行为。

由索引模型根据 Issue 内容生成。