OpenAI SDK

Point the official OpenAI SDK at the Gonka API. Nothing else changes.

Base URL: https://api.proxy.gonka.gg/v1

Environment variables some tools read

OPENAI_BASE_URL=https://api.proxy.gonka.gg/v1
OPENAI_API_KEY=sk-...

Some harnesses want OPENAI_API_BASE instead of OPENAI_BASE_URL. See Agents and IDEs.