[BuildLibrary] eliminate BuiltLibrary and BuiltOverlayLibrary

masque/file/gdsii_lazy_core.py

@@ -549,20 +549,6 @@ class OverlayLibrary(ILibrary):
         return tuple(name for name in self._order if name in self._entries)
 
 
-class BuiltOverlayLibrary(OverlayLibrary):
-    """
-    Internal overlay output returned by `BuildLibrary.build(output='overlay')`.
-
-    The type is intentionally not part of the public API. It exists so build
-    outputs can carry a `build_report` while still behaving like an
-    `OverlayLibrary`.
-    """
-
-    def __init__(self, *, build_report: Any | None = None) -> None:
-        super().__init__()
-        self.build_report = build_report
-
-
 def _iter_library_infos(library: Mapping[str, Pattern] | ILibraryView) -> Iterator[dict[str, Any]]:
     info = getattr(library, 'library_info', None)
     if isinstance(info, dict):