Honor ApplicableOccurrence in is_relating_type_compatible

Companion to the assign_type.py fix. The same class-pairing validation
added in 10ee5aef4f also gates the Bonsai-side type assignment UI via
tool.Type.is_relating_type_compatible, which the AssignType operator
uses to filter selectable objects. For annotation types (abstract
IfcTypeProduct), get_applicable_types(IfcAnnotation) is empty, so every
annotation was skipped with "No selected object can be typed by
IfcTypeProduct."

Honor the type's ApplicableOccurrence attribute as a fallback, matching
the core API fix. occurrence.is_a() handles subtypes and returns False
for unknown tokens, so free-form text is not trusted blindly.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/bonsai/bonsai/tool/type.py

@@ -107,7 +107,15 @@ class Type(bonsai.core.tool.Type):
         # RelatingType / RelatedObjects classes; the one-to-one class pairing
         # is a buildingSMART implementer agreement, not file-validation.
         schema = occurrence.file.schema
-        return relating_type.is_a() in ifcopenshell.util.type.get_applicable_types(occurrence.is_a(), schema=schema)
+        if relating_type.is_a() in ifcopenshell.util.type.get_applicable_types(occurrence.is_a(), schema=schema):
+            return True
+        # The implementer agreement map has no entry for the abstract
+        # IfcTypeProduct, which Bonsai uses for annotation types. The schema
+        # defines IfcTypeProduct.ApplicableOccurrence for exactly this purpose,
+        # so honor it. occurrence.is_a() handles subtypes and unknown tokens.
+        if applicable_occurrence := getattr(relating_type, "ApplicableOccurrence", None):
+            return occurrence.is_a(applicable_occurrence.split("/", 1)[0])
+        return False
 
     @classmethod
     def has_material_usage(cls, element: ifcopenshell.entity_instance) -> bool: