Add tests and implement boundary smoothing and cutout functionality

- Introduced tests for boundary smoothing in `test_boundary_smoothing.py`, verifying that smoothing reduces stair-step artifacts while preserving boundary integrity.
- Added tests for cutout boundary behavior in `test_cutout_boundary.py`, ensuring proper handling of boundary triangles and normal blending.
- Created `test_temporary_attributes.py` to check the cleanup of temporary attributes across depth modifier branches, ensuring no warnings are raised.
- Implemented point culling functionality in `test_validity.py`, confirming that invalid points are removed without affecting adjacent geometry.
- Developed boundary smoothing logic in `boundary_smoothing.py`, allowing for depth smoothing while maintaining edge integrity.
- Added cutout boundary management in `cutout_boundary.py`, including functions for removing boundary triangles and tapering thickness profiles.
- Implemented validity checks in `validity.py` to ensure proper deletion of invalid vertices and associated wire edges.

tests/anyimage/test_preferences.py

@@ -118,6 +118,21 @@ class PreferencesTest(BlenderTestCase):
         geometry = properties.geometry_model_enum_items(None, None)
         self.assertEqual(tuple(item[0] for item in geometry), expected)
 
+    def test_model_tiers_only_appear_in_choices(self):
+        properties = self.anyimage.properties
+        preferences = self.anyimage.preferences
+        catalog = {model["key"]: model for model in properties.model_catalog()}
+        for items in (
+            properties.geometry_model_enum_items(None, None),
+            preferences.BACKGROUND_MODEL_ITEMS,
+            preferences.UPSCALE_MODEL_ITEMS,
+        ):
+            for item, tier in zip(items, ("Fast", "Base", "Pro")):
+                label = catalog[item[0]]["label"]
+                self.assertNotIn(" | ", label)
+                self.assertEqual(item[1], f"{tier} | {label}")
+        self.assertEqual(properties.upscale_model_label("HAT_GAN_X4_SHARPER"), "HAT Sharper")
+
     def test_model_preferences_keep_valid_choices_and_normalize_retired_keys(self):
         module = self.anyimage.preferences
         stored = self.fake_bpy.context.preferences.addons["anyimage"].preferences