add env check

scripts/check_env.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -euo pipefail
+echo "python: $(python --version 2>&1)"
+python -c "import torch, sys; print('torch', torch.__version__, 'cuda_available', torch.cuda.is_available())"
+echo "code mount:"
+ls /code
+echo "scripts:"
+ls /code/scripts
+echo "gpu:"
+nvidia-smi --query-gpu=name,memory.total --format=csv,noheader || true