feat(config): default to WebSocket and migrate saved HTTP settings

tests/unit/test_responses_websocket.py

@@ -460,7 +460,8 @@ async def test_idle_connections_are_closed_and_removed(wire, monkeypatch):
 async def test_cancel_waiting_turn_keeps_active_chain_and_idle_cleanup(wire, monkeypatch):
     from artemis.llm import websocket
 
-    monkeypatch.setattr(websocket, "IDLE_SECONDS", 0.05)
+    # Only shorten the final idle interval; scheduler latency must not break the first chain.
+    monkeypatch.setattr(websocket, "IDLE_SECONDS", 60)
     wire.gate = asyncio.Event()
     async with model(wire) as raw:
         history = [HumanMessage(content="First")]
@@ -475,6 +476,7 @@ async def test_cancel_waiting_turn_keeps_active_chain_and_idle_cleanup(wire, mon
             await queued
         wire.gate.set()
         result = await first
+        monkeypatch.setattr(websocket, "IDLE_SECONDS", 0.01)
         await raw.ainvoke(
             [*history, result, HumanMessage(content="Next")], prompt_cache_key="task:operator"
         )