feat(llm): support incremental Responses WebSocket transport

artemis/config/settings.py

@@ -16,6 +16,7 @@
 
 import os
 from pathlib import Path
+from typing import Literal
 
 from dotenv import load_dotenv
 from pydantic import Field, SecretStr, model_validator
@@ -109,6 +110,7 @@ class Settings(BaseSettings):
     OPENAI_BASE_URL: str | None = "https://api-n-cd.playones.com/v1"
     OPENAI_MODEL: str = Field(default=DEFAULT_MODEL, min_length=1)
     OPENAI_TIMEOUT_SECONDS: float = Field(default=300.0, gt=0)
+    OPENAI_TRANSPORT: Literal["http", "websocket"] = "http"
     # Environment only; deliberately absent from the saved UI/task configuration.
     OPENAI_USE_SYSTEM_PROXY: bool = False
     OPENAI_MAX_RETRIES: int = Field(default=5, ge=0, le=10)