fix: correct TestClient imports to use starlette.testclient

tests/test_api.py

@@ -34,6 +34,4 @@ def test_summarize_endpoint_validation_error():
         "/api/v1/summarize/",
         json={"text": ""}
     )
-    assert resp.status_code == 422
-
-
+    assert resp.status_code == 422

tests/test_api_errors.py

@@ -30,6 +30,4 @@ def test_request_id_header_propagated(sample_text, mock_ollama_response):
     with patch('httpx.AsyncClient', return_value=StubAsyncClient(post_result=stub_response)):
         resp = client.post("/api/v1/summarize/", json={"text": sample_text})
         assert resp.status_code == 200
-        assert resp.headers.get("X-Request-ID")
-
-
+        assert resp.headers.get("X-Request-ID")