## Summary

Describe the problem and the smallest change that solves it.

## Validation

- [ ] `make -C c check`
- [ ] CUDA changes were tested with `make -C c cuda-test` (if applicable)
- [ ] Performance claims include hardware, commands, and repeatable measurements

## Compatibility

- [ ] The default CPU build remains dependency-free
- [ ] No model files, generated binaries, or benchmark artifacts are included