OpenAI-compat: gen_api_answer.py --openai-api-base /v1, not the API server

Working config (gen_api_answer.py --openai-api-base /v1)

The consumer path is fastchat/llm_judge/gen_api_answer.py. --openai-api-base sets legacy openai.api_base to the /v1 root. That is the OpenAI-compatible join for answering against a remote Chat Completions host.

docs/openai_api.md is the server (fastchat.serve.openai_api_server). Do not start a controller or worker to talk to a hosted /v1. Override default gpt-3.5-turbo with a catalog id.

A Chat Completions host whose public catalog is GET https://api.pzero.studio/v1/models (no key) fits --openai-api-base if the value is https://api.pzero.studio/v1.

export OPENAI_API_KEY=<Bearer key for that host>
python gen_api_answer.py \
  --model deepseek-v4-flash \
  --openai-api-base https://api.pzero.studio/v1

Keep embeddings off this host.