Refactor depth node groups and simplify options

- Removed `Smooth Weight` input from `O Image Depth Plane`, `O Image Depth Cutout`, and `O Image Depth Panorama` to streamline the interface and maintain consistent boundary smoothing behavior.
- Adjusted the `Reference Depth` input to appear last in the options panel for better organization, reflecting its role as a calibration value.
- Consolidated the `expand_smooth()` function to only accept necessary parameters, eliminating unused branches related to `Smooth Weight` and `pin_sharp`.
- Updated related tests and node assets to ensure functionality remains intact and consistent with the new structure.
- Introduced new specifications to document the changes and ensure compliance with the updated requirements.

tests/support/depth_surface.py

@@ -91,6 +91,30 @@ def assert_closed(faces):
     assert edges and set(edges.values()) == {2}, Counter(edges.values())
 
 
+def assert_single_vertex_fans(faces):
+    """Every vertex must close one face fan so touching sheets stay identifiable."""
+    incident = {}
+    for index, face in enumerate(faces):
+        for start, end in zip(face, (*face[1:], face[0])):
+            edge = tuple(sorted((start, end)))
+            incident.setdefault(start, {}).setdefault(edge, []).append(index)
+            incident.setdefault(end, {}).setdefault(edge, []).append(index)
+    for vertex, edges in incident.items():
+        shared = {}
+        for faces_at_edge in edges.values():
+            assert len(faces_at_edge) == 2, (vertex, faces_at_edge)
+            first, second = faces_at_edge
+            shared.setdefault(first, set()).add(second)
+            shared.setdefault(second, set()).add(first)
+        assert all(len(neighbors) == 2 for neighbors in shared.values()), vertex
+        reached, pending = {next(iter(shared))}, [next(iter(shared))]
+        while pending:
+            for neighbor in shared[pending.pop()] - reached:
+                reached.add(neighbor)
+                pending.append(neighbor)
+        assert len(reached) == len(shared), vertex
+
+
 def component_count(faces):
     adjacency = {}
     for face in faces: