Scrollbar插件无法触发画布事件blank:mousewheel

### 问题描述

两个问题：

- 蓝色区域内无法触发 `blank:mousewheel` 事件
- 蓝色区域外无法实现画布的缩放



### 重现链接

[https://codesandbox.io/p/sandbox/quizzical-lumiere-dl84t6](https://codesandbox.io/p/sandbox/quizzical-lumiere-dl84t6)

### 重现步骤

使用Scroller插件

### 预期行为

滚动区域任何位置都能触发 `blank:mousewheel` 事件，都可以实现画布缩放。

### 平台

- 操作系统: Windows
- 网页浏览器: Google Chrome
- X6 版本: All

### 屏幕截图或视频（可选）

_No response_

### 补充说明（可选）

_No response_

Start with the linked CodeSandbox reproduction and the Scroller plugin behavior around blank:mousewheel. Verify the two reported cases on Windows Chrome: scrolling inside and outside the blue area should both trigger the event and allow canvas zooming. Done means the expected behavior works throughout the scrollable region without regressing the existing Scroller behavior.

Written by the indexing model from the issue text.