[FEATURE] Add config option to disable behavior where rectangular zoom selection becomes full height selection if mouse Δy is close to 0

Hi,

There is a feature that makes that a rectagular selection on a heatmap becomes a "full height selection" if the mouse Δy is close to 0 (I mean vertical distance between start point and end point).

Is there a setting to turn this feature off? I didn't find it in the documentation.

Example here I wanted to select a rectangle of height 2 pixels, but it moved into a full height selection:

Thanks!

issue 中未指定文件或测试。首先追踪 heatmap 的矩形缩放选择行为及其配置选项，然后检查相关设置是如何记录的。完成标准是：配置选项可以禁用接近零的鼠标 Δy 转换，同时默认保留现有行为，并覆盖两种模式。