[Feature]: 批量将对话放入项目

[qingchunnh]

Affected area

Frontend / UI

Problem or use case

目前所有对话界面无法批量将对话放入项目。用户只能逐个将对话移至项目，当需要整理大量历史对话到同一项目时非常低效。

Proposed behavior

在所有对话页面的批量选择模式的工具栏中，新增移至项目按钮，与现有的归档/撤销共享/删除/取消按钮并列。

Alternatives considered

No response

Compatibility, deployment, or migration impact

No response

Documentation or API contract impact

No response

Pre-submit checklist

• I searched existing issues and pull requests.
• This request is focused on one feature or improvement.
• I described user-facing, API, configuration, or deployment impact where relevant.