fix(ci): clean stale test binaries from PVC before GPU tests

Cargo incremental compilation on persistent PVC reuses old test
binaries even when source changed. Force cargo clean -p for ML crates
to ensure fresh compilation with latest max_bars and test fixes.

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

infra/k8s/argo/gpu-test-pipeline-template.yaml

@@ -208,6 +208,9 @@ spec:
             export PATH="${CARGO_HOME}/bin:${PATH}"
             export CUDA_COMPUTE_CAP={{workflow.parameters.cuda-compute-cap}}
 
+            # --- Clean stale test binaries (PVC incremental cache) ---
+            cargo clean -p ml -p ml-core -p ml-dqn -p ml-ppo 2>/dev/null || true
+
             # --- PTX cache invalidation ---
             # Purge stale cached PTX if any CUDA kernel source changed since last run.
             bash scripts/ptx-cache-invalidate.sh "${CARGO_TARGET_DIR}/.ptx_cache"