feat: 推进SCDM-first后端接入和大模型编辑优化

step_editor/__init__.py

@@ -1,11 +1,13 @@
 from __future__ import annotations
 
-from .model import StepModel
-
 __all__ = ["StepEditorWindow", "StepModel", "main"]
 
 
 def __getattr__(name: str):
+    if name == "StepModel":
+        from .model import StepModel
+
+        return StepModel
     if name in {"StepEditorWindow", "main"}:
         from .app import StepEditorWindow, main