infra: add nsight-systems-cli to ci-builder Docker image

Enables nsys profiling for CUDA graph node-level traces on H100.
Use --sanitizer nsys in argo-train.sh to activate.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

infra/docker/Dockerfile.ci-builder

@@ -54,6 +54,11 @@ RUN curl -fsSL https://downloads.rclone.org/v1.69.1/rclone-v1.69.1-linux-amd64.z
 # clippy pre-installed
 RUN rustup component add clippy
 
+# Nsight Systems CLI — GPU profiling for CUDA graph node-level traces
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    nsight-systems-cli \
+    && rm -rf /var/lib/apt/lists/*
+
 # CUDA env
 ENV CUDA_HOME=/usr/local/cuda
 ENV PATH="${CUDA_HOME}/bin:${PATH}"