Add uv support and update Python documentation

[lmdevv]

What problem are you trying to solve?

Devbox’s current Python documentation only covers pipenv and poetry for virtual environment management.

However, uv has quickly become a preferred modern Python tool, providing faster dependency management and built-in environment creation.

Integrating or documenting uv would improve reproducibility and developer experience for Python users.

What solution would you like?

Improved documentation and maybe uv plugin to handle shell venv

Alternatives you've considered

No response