Further numerical robustness issue in path rendering

Nobody has claimed this yet.

Hello, I've quietly followed this project for quite some time, and thank you for this great work!

I am aware the path rendering algorithm is numerically tricky, and many numeric issues have already been resolved in the past. But unfortunately I still run into one issue here. The following incorrectly rendered image is produced by latest vello on the main branch (8a84a4abf7aaabdb7de82e3d9d86ed427ad21638); the correct image should be a white filled square.


To reproduce, replace the function `add_shapes_to_scene` in `examples/simple/src/main.rs` with the following code:

```
fn add_shapes_to_scene(scene: &mut Scene) {
use vello::kurbo::PathEl::*;

let path = [
MoveTo((0.0, 0.0).into()),
LineTo((1000., 0.).into()),
LineTo((1000., 1000.).into()),
LineTo((0., 1000.).into()),
LineTo((-1.87016292e-06, 923.848633).into()),
LineTo((1.87016292e-06, 156.151367).into()),
ClosePath,
];

scene.fill(
vello::peniko::Fill::NonZero,
Affine::IDENTITY,
Color::new([1.,1.,1.,1.]),
None,
&path,
);
}
```

Start by replacing add_shapes_to_scene in examples/simple/src/main.rs with the supplied path and run the simple example to reproduce the incorrect rendering. Trace the numerical path-rendering behavior responsible for the result; done means this path renders as the expected white filled square.

Written by the indexing model from the issue text.