Health checkpoint

Can you please implement /health API endpoint?
Like in llama.cpp: https://github.com/ggml-org/llama.cpp/blob/master/tools/server/README.md#get-health-returns-health-check-result
Main reason: for llama-swap to monitor startup process
For now, ds4 is runnable under llama-swap using `checkEndpoint: /v1/models` custom configuration