Faceplugin-ltd/Open-Source-Face-Recognition-SDK ? reverse-engineered prompt

Build me a simple Python face recognition SDK that runs locally on Windows and Linux, with no cloud calls and no data leaving the machine.

I want it to take an image file, find every face in it, give me each face box, facial landmark points, and a face embedding I can use to compare people. It should also include a clean way to compare two face feature vectors and return a similarity score, so I can tell if two images are likely the same person. Please make it easy to use from one main class or module, and include a small test or demo script I can run right away to verify it works.

Keep the setup straightforward, use the dependencies needed for Python 3.9 or newer, and make sure it works well on CPU only since GPU should be optional. If you need to look up current model or library docs online, go ahead.