Qwen 0.6B Megakernel for RTX 5090

This megakernel is aggressively optimized for Qwen3-0.6B (bf16) shapes to be run on an RTX 5090.

More details on this blogpost: https://blog.alpindale.net/posts/5090_decode_optimization/

Backend	tok/s	ms/tok	Speedup
PyTorch (HF)	123.3	8.11	1.00x
Megakernel	1036.3	0.99	8.40x

To use this:

uv pip install -r requirements.txt
python -m qwen_megakernel.bench

Not tested on any other GPU, and likely won't run or work. Needs at least CUDA 12.8.

Credits

Based on Elliot Arledge's MegaQwen for the RTX 3090 GPU.