Remove torch/torchvision: use ZeroGPU pre-installed version

ZeroGPU pre-installs torch; torch==2.8.0 on PyPI lacks CUDA wheels
causing build failures. Previous cb96191 proved removal works.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

requirements.txt

@@ -13,8 +13,6 @@ pillow==11.3.0
 safetensors==0.6.2
 timm==1.0.20
 tokenizers==0.22.1
-torch==2.8.0
-torchvision==0.23.0
 torchdiffeq==0.2.5
 torchsde==0.2.6
 tqdm==4.67.1