[Bug]: 输入框和流式输出区域的高度设计问题

### Summary

<img width="1652" height="187" alt="Image" src="https://github.com/user-attachments/assets/d3032ca5-6fed-4a64-bacc-35b0126a1e33" />

### Area

Desktop app

### Reproduction or evidence

如上图，是这样设计的还是bug

### Environment, if relevant

_No response_