ci: disable auto GPU tests on push (manual only, H100 is expensive)

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

infra/k8s/argo/ci-pipeline-template.yaml

@@ -142,10 +142,12 @@ spec:
                   value: "{{workflow.parameters.commit-sha}}"
             when: "{{tasks.detect-changes.outputs.parameters.needs-infra}} == true"
 
+          # GPU tests: manual only (argo submit --from=wftmpl/gpu-test-pipeline).
+          # Auto-trigger disabled — H100 nodes are expensive, run on demand.
           - name: gpu-test
             depends: "detect-changes"
             template: submit-gpu-test
-            when: "{{tasks.detect-changes.outputs.parameters.ml-changed}} == true"
+            when: "false"
 
     # ── detect-changes: classify changed files to gate downstream steps ──
     - name: detect-changes