Repair ONNX TensorScatter circular KV-cache indexing and run the offline reference inference fixture.

Repair ONNX TensorScatter circular KV-cache indexing and run the offline reference inference fixture.: a task in MiMo-V2.6-RL-oss: Agentic RL Environments (MiMo RL release). The workspace under /app/vendor/onnx is a frozen slice of a tensor operator used for bounded attention KV-cache updates…