Refresh DeepSeek V4 GB300 TRT-LLM AgentX metrics (#2774)

* config(dsv4): enable GB300 TRT-LLM metrics

* chore: add DeepSeek V4 metrics refresh changelog

* fix(dsv4): require iteration metrics

* fix(agentx): aggregate TensorRT-LLM metrics

* fix(agentic): target the SRT frontend host

* fix(trtllm): decouple metrics from KV events

* Avoid detailed TRT metrics overhead

* Use metrics-only Dynamo publisher

* fix: align DSv4 AgentX offload metadata

* docs: consolidate metrics refresh changelog [skip-sweep]