## 1. Implementation

- [x] 1.1 Implement GPU signature detection (NVIDIA/AMD), persistent client UUID fallback, and SHA-256 hashing in `UnitPasCubeScreen.pas`.
- [x] 1.2 Modify `TPasCubeScreen.SubmitBenchmarkResults` to include the `machine_hash` in the JSON payload.
- [x] 1.3 Verify the build compiles successfully.
