Show HN: TurboGPT: train 22KiB transformer in 13s

TurboGPT is a tiny byte-level GPT training system implemented in CUDA C++ and released under the MIT license. It can train a 22KiB transformer in 13 seconds. Users can build it on Linux/NixOS using nix-build or on Windows with Visual Studio 2022 and CUDA 13.4 using .\build.ps1. Training runs store checkpoints and generate TensorBoard-compatible logs, with a reported result of 2.5295 BPB after 1.5G training tokens on hn1g.