LCORE-438: Add detection of GPU Python libs in image building

Author: matysek

Containerfile-gpu

@@ -38,8 +38,8 @@ RUN uv lock && uv sync --locked --no-install-project
 # Installing separately from its dependencies allows optimal layer caching
 RUN uv sync --locked
 
-# Test PyTorch was installed with default GPU linux backend (CUDA)
-#RUN uv run python -c "import torch; print(torch.__version__); assert 'cpu' not in torch.__version__;"
+# Test PyTorch was installed with GPU libraries (CUDA)
+RUN uv run python -c "from nvidia import cuda_runtime"
 
 # Add executables from .venv to system PATH
 ENV PATH="/rag-content/.venv/bin:$PATH"