Saintydroid/scikit-learn ? reverse-engineered prompt

Build me a Python machine learning library like scikit learn, with a clean, easy to use API for training and using common models. I want it to support things like classification, regression, clustering, preprocessing, model selection, and simple plotting helpers, with good documentation and examples so someone can learn it quickly.

Make it feel like a real open source library, not just a demo. Include installation instructions, a basic test suite, and a few example scripts showing how to fit models, make predictions, and evaluate results. Use modern Python and keep the code organized so it would be realistic to maintain. If you need to check current docs or best practices online, go ahead and look them up.

Please also add clear contribution notes, a changelog style section, and make sure the project can be installed and run locally without a lot of setup.