feat: add router replay(R3) for megatron engine #1531

Job	Run time
Install test (ubuntu-latest, Python 3.12)	1m 18s
Install test (Linux, CUDA extras, sglang)	1m 27s
Install test (Linux, CUDA extras, vllm)	1m 30s
Install test (macos-latest, Python 3.12)	1m 20s
Install test (Docker ${{ matrix.variant }} image)	0s
	5m 35s

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