ShiqiYu/libfacedetection ? reverse-engineered prompt

Build me a fast face detection project in C++ that can find faces in images and from a webcam, and keep it lightweight so it does not depend on OpenCV or other big libraries unless I choose the ONNX demo path. I want a simple library I can drop into another app, plus a couple of working examples for detecting faces from an image file and from a live camera feed. Please make it easy to compile on Windows, Linux, and ARM too, and use the speed optimizations that make sense for each platform. If there are extra sample builds for OpenCV DNN, Android, or Rust support in the repo, wire those up enough that I can try them without too much fuss. Also include clear build and run instructions, and if you need to check current docs online for anything platform specific, go ahead and do that.