Add comprehensive tests for cutout and mesh functionalities

- Introduced `test_cutout.py` to validate cutout pie menu behavior, image lasso options, and mesh detail calculations.
- Added `test_mesh.py` to ensure correct tangent normal rasterization, plane source topology, and depth surface evaluations.
- Created `test_mesh_blender.py` to verify material node groups, tangent baking, and local cutout building from Blender images.
- Implemented tests for handling alpha regions and ensuring geometry nodes maintain expected behavior.

tools/validate_balloon_asset.py

@@ -99,13 +99,14 @@ def main():
     material_group = material_node_group(
         surface_group_name=BALLOON_MATERIAL_NODE_GROUP_NAME,
     )
-    normal_map = next(
-        node
+    normal_maps = {
+        node.space
         for node in material_group.nodes
         if node.bl_idname == "ShaderNodeNormalMap"
-    )
-    assert normal_map.space == "TANGENT"
-    assert abs(input_socket(material_group, "Normal Strength").default_value - 0.5) < 1e-6
+    }
+    assert normal_maps == {"TANGENT", "OBJECT"}
+    assert input_socket(material_group, "Object Space").default_value is False
+    assert input_socket(material_group, "Normal Scale").default_value == 1.0
 
     source_image = bpy.data.images.new("Reuse Source", 2, 1)
     shared_normal = bpy.data.images.new("Shared Normal", 2, 1)
@@ -115,8 +116,6 @@ def main():
     material = bpy.data.materials.new("Unrelated Material Name")
     mark_balloon_material(material, source_image, shared_normal)
     assert reusable_balloon_material(
-        "unused",
-        "unused",
         source_image,
         normal_required=True,
     ) is material