[Bug]: 鼠标中键拖动画布存在偏差

### Describe the bug / 问题描述

在画布空白处使用鼠标中键拖动画布正常，
但是把鼠标放到一个node上，再通过中键拖动画布时，
鼠标和node的相对位置会出现一些偏差，貌似和zoom系数有关系。

### Reproduction link / 复现链接

_No response_

### Steps to Reproduce the Bug or Issue / 重现步骤

_No response_

### Version / 版本

🆕 5.x

### OS / 操作系统

- [ ] macOS
- [x] Windows
- [ ] Linux
- [ ] Others / 其他

### Browser / 浏览器

- [x] Chrome
- [ ] Edge
- [ ] Firefox
- [ ] Safari (Limited support / 有限支持)
- [ ] IE (Nonsupport / 不支持)
- [ ] Others / 其他

Reproduce the issue in G6 5.x on Windows with Chrome by placing the pointer over a node, changing the zoom, and dragging the canvas with the middle mouse button. Trace the canvas middle-button drag handling and compare the pointer-node offset with dragging from blank space. Done means the relative position remains stable regardless of zoom.

Written by the indexing model from the issue text.