v1.3.1

Fixes

• CPU image reduced from ~12.7 GB to ~2.4 GB. The default build was silently pulling the CUDA torch wheel from PyPI instead of the CPU-only wheel.
• Switched to a multi-stage Docker build with a virtual environment, eliminating ghost install layers that kept deleted packages on disk.
• Removed triton (545 MB, only needed for torch.compile()) from all images.
• Fixed a duplicate opencv library left behind by the previous --force-reinstall approach.