Improve generated crossing geometry near sharp angles

> This case is fixed in a simple way, but it reveals more problems:
>
> `https://a-b-street.github.io/speedwalk/#19.95/52.7923616/13.2608191`
>
>
> We really need to handle the angle of roads better, or look for the "corner" in the generated sidewalks to place things better. (This might introduce more dependency of bulk operation steps, because then we have to generate sidewalks before crossing nodes.)
>

_Originally posted by @dabreegster in [#83](https://github.com/a-b-street/speedwalk/issues/83#issuecomment-3800028316)_

The issue references a visual problem with crossing geometry near sharp angles in a map visualization. Start by examining the linked URL to see the rendering issue. Look for code that generates sidewalks and crossing nodes, likely in the geometry processing or rendering modules. Understanding the dependency between sidewalk generation and crossing node placement is key. 'Done' means the crossing geometry is improved without breaking existing functionality.

Written by the indexing model from the issue text.