[Bug]: 左侧功能区无法展开

### Version line

v2 — Go rewrite (1.x), main-v2 (active development)

### Exact version

1.1.0

### What happened?

<img width="300" height="362" alt="Image" src="https://github.com/user-attachments/assets/1505407a-c5cc-4b42-a5de-b0d54367a757" />

左侧收起后，无法展开，找不到入口，拖拽区域也没用

### Steps to reproduce

点击左侧收起

### OS / platform

macos 26.5

### Relevant logs or output

```shell

```