fix(ci): add libcuda.so.1 stub for test stage on GPU-less nodes

The backtesting crate dynamically links to libcuda.so.1 via candle.
NVIDIA CUDA dev images include stubs at /usr/local/cuda/lib64/stubs/
but only as libcuda.so (not .so.1). Create the symlink both in the
Dockerfile (for future builds) and inline in the test script (for
the current image).

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

.gitlab-ci.yml

@@ -81,6 +81,9 @@ test:
   stage: test
   needs: [check]
   script:
+    # Create libcuda.so.1 symlink to stub (GPU-less CI nodes)
+    - ln -sf /usr/local/cuda/lib64/stubs/libcuda.so /usr/local/cuda/lib64/stubs/libcuda.so.1
+    - export LD_LIBRARY_PATH="/usr/local/cuda/lib64/stubs:${LD_LIBRARY_PATH}"
     - cargo test --workspace --lib
 
 # --------------------------------------------------------------------------

infra/docker/Dockerfile.ci-builder

@@ -46,5 +46,9 @@ ENV CUDA_HOME=/usr/local/cuda
 ENV PATH="${CUDA_HOME}/bin:${PATH}"
 ENV LD_LIBRARY_PATH="${CUDA_HOME}/lib64:${LD_LIBRARY_PATH}"
 
+# libcuda.so.1 stub — satisfies runtime linking on GPU-less CI nodes
+# (the stubs dir has libcuda.so but binaries want libcuda.so.1)
+RUN ln -sf /usr/local/cuda/lib64/stubs/libcuda.so /usr/local/cuda/lib64/stubs/libcuda.so.1
+
 # Verify
 RUN rustc --version && cargo --version && git --version && protoc --version && sccache --version && make --version && nvcc --version