fix type-check for z-image transformer (#12739)

* allow type-check for ZImageTransformer2DModel

* make fix-copies

Author: DefTruth

src/diffusers/__init__.py

@@ -991,6 +991,7 @@
             WanAnimateTransformer3DModel,
             WanTransformer3DModel,
             WanVACETransformer3DModel,
+            ZImageTransformer2DModel,
             attention_backend,
         )
         from .modular_pipelines import ComponentsManager, ComponentSpec, ModularPipeline, ModularPipelineBlocks

src/diffusers/utils/dummy_pt_objects.py

@@ -1698,6 +1698,21 @@ def from_pretrained(cls, *args, **kwargs):
         requires_backends(cls, ["torch"])
 
 
+class ZImageTransformer2DModel(metaclass=DummyObject):
+    _backends = ["torch"]
+
+    def __init__(self, *args, **kwargs):
+        requires_backends(self, ["torch"])
+
+    @classmethod
+    def from_config(cls, *args, **kwargs):
+        requires_backends(cls, ["torch"])
+
+    @classmethod
+    def from_pretrained(cls, *args, **kwargs):
+        requires_backends(cls, ["torch"])
+
+
 def attention_backend(*args, **kwargs):
     requires_backends(attention_backend, ["torch"])