Refact selfhost BYOK

[ukrolelo]

Tryed this:

chat_endpoint: "http://localhost:8008/v1/chat/completions"
chat_model: "qwen2.5/coder/1.5b/instruct"

with this error:

Error: 422 Unprocessable Entity: [{"type":"missing","loc":["body","messages"],"msg":"Field required","input":{"model":"qwen2.5/coder/1.5b/instruct","stream":true,"temperature":0.0,"max_completion_tokens":4096,"stream_options":{"include_usage":true},"prompt":"<|im_start|>user\nhello\n\n<|im_start|>assistant\n"},"url":"https://errors.pydantic.dev/2.10/v/missing"}]
Click to retry```