[diffusion][feature] Add LingBot-Video T2I and TI2V generation modes (#5311)

Signed-off-by: wtz2333 <2955110911@qq.com>
Co-authored-by: Claude <noreply@anthropic.com>

tests/entrypoints/openai_api/test_image_server.py

@@ -223,6 +223,17 @@ def test_client(mock_async_diffusion):
     return TestClient(app)
 
 
+@pytest.fixture
+def lingbot_test_client(test_client):
+    test_client.app.state.stage_configs = [
+        SimpleNamespace(
+            stage_type="diffusion",
+            engine_args={"model_class_name": "LingBotVideoPipeline"},
+        )
+    ]
+    return test_client
+
+
 @pytest.fixture
 def async_omni_test_client():
     """Create test client with mocked AsyncOmni engine."""