Extend the internode gRPC benchmark driver with P2 request-only, canary, after, and rollback phases. The request-only phase proves that requesting msgpack-only without fleet confirmation keeps compatibility JSON fields, while canary and rollback materialize the operator states needed for mixed-version convergence without claiming real fleet soak evidence. Verification: - scripts/test_internode_grpc_ab_bench.sh - bash -n scripts/run_internode_grpc_ab_bench.sh scripts/test_internode_grpc_ab_bench.sh - git diff --check Co-authored-by: heihutu <[email protected]>