SVG importer does not apply root viewBox scaling to stroke widths

从 SVG 导入器的入口点开始，使用报告中的最小 SVG 示例重现问题，并比较线条描边与矩形高度。跟踪 root width/height 和 viewBox 缩放的应用方式，然后验证当缩放因子为 0.25 时，两个对象都以相同的 20 单位厚度进行渲染。

When the document width/height is different from the viewBox, geometry is scaled accordingly but not stroke widths (even when the aspect ratio is the same for both). Here's a minimal working (or in this case, failing?) example:

<svg xmlns="http://www.w3.org/2000/svg" width="240" height="120" viewBox="0 0 960 480">
  <line x1="120" y1="140" x2="840" y2="140"
        stroke="#d62828" stroke-width="80" stroke-linecap="butt"/>
  <rect x="120" y="300" width="720" height="80" fill="#1565c0"/>
</svg>

These two objects should have the same visual thickness: one is a line with stroke width of 80, another is a rectangle with height 80, no stroke.
Opening this file directly in Safari shows the intended result (also reproduced with macOS Preview, Inkscape, Firefox and Chrome):

But importing this in Graphite gives this:

I reproduced this issue on:

• RC6 macOS desktop app
• Graphite web app
• https://dev.graphite.art with the following About this release info:

Release Series: Alpha 5
Branch: master
Commit: e725f550
2026-09-07 02:57 Eastern Time

The issue is that the viewport is 240 × 120 while the viewBox is 960 × 480, giving a scale factor of 0.25. Both the 80-unit stroke width and the 80-unit rectangle height should render as 20 units/pixels thick. A workaround for now is simply to use the same values for width/height as for the viewBox.

Possibly related: PR #3942, issue #2435.