tests: migrate LLM tests to Settings-based constructor API

Replace the old `model=` / `params=InputParams(...)` style with the
new `settings=<Service>.Settings(...)` form across LLM service tests.

tests/test_novita_llm.py

@@ -22,7 +22,9 @@ async def test_novita_llm_stream_closed_on_cancellation():
     This prevents socket leaks when the pipeline is interrupted (e.g., user interruption).
     """
     with patch.object(NovitaLLMService, "create_client"):
-        service = NovitaLLMService(api_key="test-key", model="test-model")
+        service = NovitaLLMService(
+            api_key="test-key", settings=NovitaLLMService.Settings(model="test-model")
+        )
         service._client = AsyncMock()
 
         stream_closed = False