Older NVIDIA GPUs get a CUDA torch build with no kernels for them #732

Split out of #723.

What goes wrong

On a GTX 970 (compute capability 5.2) with a driver reporting CUDA 13, first-run setup installs CUDA torch, verification fails with "no kernel image is available for execution on the device", and the app falls back to CPU. The GPU would work with an older torch build.

Why

For a CUDA 13 driver the wheel list is cu128 only. The cu128 torch build has no kernels below sm_61 (Pascal), so Maxwell cards such as the GTX 9xx series can never pass. The cu124 and cu118 builds are never tried.

Constraints

• The compute capability is already detected before choosing a wheel.
• Whether cu124 or cu118 still ship sm_50 and sm_52 kernels on Windows has to be checked against the published wheels, not assumed.