Small Improvements

[mbway]

Miscellaneous maintenance and small features. I can split these out into separate PRs if you prefer.

Medium

• site installation
  • handle installation into usercustomize.py
  • provide presets so the most common use cases (debug and release with default features) is handled by the automatic installation. Let me know if you have ideas for any other presets that may be useful. The user can of course go and edit sitecustomize.py directly, and site info helps them find it.
  • option to force/overwrite when using site install (more useful now that there are presets to choose from)
  • the default site installation handles when maturin_import_hook cannot be imported (previously if the user uninstalls the import hook an error would be printed)

Small

• use uv in tests instead of pip when available (replacing virtualenv command)
• update pre-commit hook versions
• capitalisation and spelling and wording fixes
• added link to maturin.rs documentation in the README
• replaced some documentation with a link to the maturin.rs hosted version
• handle FileNotFoundError in maturin_import_hook version command
• functions to check if the hook is installed

Usercustomize.py

Reading the site module documentation, the difference between usercustomize and sitecustomize isn't totally clear.

The distinction is more important when using the system python installation, because site-packages is not user-writable without root. usercustomize.py can be found at ~/.local/pythonX.Y/site-packages/usercustomize.py (by default) so it's shared between interpreters. By default, virtualenvs do not look here and usually the virtualenv is user-writable so using sitecustomize.py is not a problem. It still makes sense to have sitecustomize.py as the default location I think but it's nice to have the option of using either.