siupune/KeyHunt-Cuda-2 ? reverse-engineered prompt

Build me a small educational demo that shows how Bitcoin style key searching works, but only in a toy sandbox with fake data and no real wallets or real private keys.

I want it to let me enter a start and end range, pick CPU or GPU, and then simulate scanning that range for a matching hash or address. It should show progress, speed, and the number of items checked, and save any matches it finds into an output file. Please keep the interface simple and make sure it can run in single address mode or range mode, with clear help text for the available options.

If anything in the current code is experimental or broken, clean it up so it builds reliably and explain any setup steps I need on Windows or Linux. If you need to look up current CUDA or compiler docs online, go ahead.