reafator pipeline stage/step pipeline (#1368)

Signed-off-by: asukaqaq-s <1311722138@qq.com>

vllm_omni/diffusion/data.py

@@ -464,6 +464,9 @@ class OmniDiffusionConfig:
     # Diffusion pipeline Profiling config
     enable_diffusion_pipeline_profiler: bool = False
 
+    # Step mode settings
+    step_execution: bool = False
+
     @property
     def is_moe(self) -> bool:
         num_experts = self.tf_model_config.get("num_experts", None)