fix(azure_ai): use correct 'input_image' key for FLUX.2-pro image editing (#26698)

The Black Forest Labs API for FLUX.2-pro image editing expects the
base64-encoded image under the key "input_image", not "image".

Using the wrong key ("image") causes the API to silently ignore the
field, so no image is passed to the model — making the bug very hard
to detect since no error is returned.

Fixes #26698

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

litellm/llms/azure_ai/image_edit/flux2_transformation.py

@@ -112,7 +112,7 @@ class AzureFoundryFlux2ImageEditConfig(OpenAIImageEditConfig):
         # Build request body with required params
         request_body: Dict[str, Any] = {
             "prompt": prompt,
-            "image": image_b64,
+            "input_image": image_b64,
             "model": model,
         }