feat 新增sketch 背后视角图

fix

app/service/design_fast/pipeline/__init__.py

@@ -1,3 +1,4 @@
+from .back_perspective import BackPerspective
 from .color import Color
 from .contour_detection import ContourDetection
 from .keypoint import KeyPoint
@@ -13,6 +14,7 @@ __all__ = [
     'KeyPoint',
     'ContourDetection',
     'Segmentation',
+    'BackPerspective',
     'Color',
     'PrintPainting',
     'Scaling',