feat: add basic uv guide

[tobiasdiez]

Adds a guide on uv, focusing mostly on the day-to-day usage. How various parts (dependency groups, build system, etc) is already covered pretty well in the other guides.

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📚 Documentation preview 📚: https://scientific-python-cookie--829.org.readthedocs.build/

[henryiii]

Good idea, I'm just not sure of the categorization (maybe it's a tutorial? Guides is getting quite large), and might want to make it a bit more general. I'll try to help with it after a few things like the AI page are done.

[tobiasdiez]

Good idea, I'm just not sure of the categorization (maybe it's a tutorial? Guides is getting quite large), and might want to make it a bit more general. I'll try to help with it after a few things like the AI page are done.

Thanks for the feedback. What do you mean with "make it a bit more general"?

[henryiii]

Most importantly for now, the name: I want to avoid putting tool names into the link (/guides/mypy is an example of what not to do!). For now, this should be similar to th e /guides/tasks page, general link, but focused on one tool.

I can imagine eventually we'd want to follow this up with a similar "pixi" guide - either tabs on this page, or a separate page (in which case, something with uv in it might make sense - you can see why I'm not sure yet!).

Edit: after #835, I think calling this "uv" and adding "pixi" eventually, in a nested subsection, is fine.