This PR is a bit overwhelming and touches almost all the files but this is the best time to do this b/c we have only 1 real PR pending. Here we have:

• all lints in ruff are enabled
• many docstrings improvements
• code should be all typed now
• small performance fixes
• some functions are now kwargs only and this may be seen as a breaking change, next version should reflect that

I'm planning on self-merging this to avoid conflicts with upcoming PRs.