feat: 完善特征编辑和选择稳定性

step_editor/__init__.py

@@ -1,6 +1,13 @@
 from __future__ import annotations
 
-from .app import StepEditorWindow, main
 from .model import StepModel
 
 __all__ = ["StepEditorWindow", "StepModel", "main"]
+
+
+def __getattr__(name: str):
+    if name in {"StepEditorWindow", "main"}:
+        from .app import StepEditorWindow, main
+
+        return {"StepEditorWindow": StepEditorWindow, "main": main}[name]
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")