fix: sanitize OMP_NUM_THREADS at 3 levels to prevent libgomp crash on HF Spaces

fix: override OMP_NUM_THREADS to fix libgomp crash on HF Spaces

fix: remove CUDA assertion from Docker build verification

fix: split nnunetv2 install to preserve CUDA PyTorch in Docker

fix: enable nnunetv2 in requirements.txt, use CUDA base image in Dockerfile

feat: add HF Spaces Docker deployment