Python: Title: DevUI Fix WorkflowFailedEvent error extraction (#2706)

* Title: Fix WorkflowFailedEvent error extraction to use details instead of error Body:
Summary
Fixed WorkflowFailedEvent mapping to extract error message from details.message instead of non-existent error attribute
Added support for including details.extra context in error messages when present
Problem
The WorkflowFailedEvent handler in _mapper.py was reading event.error, but WorkflowFailedEvent uses a details attribute (of type WorkflowErrorDetails), not error. This caused all workflow failures to display "Unknown error" in the UI instead of the actual error message.
Fix
Updated the handler to match the pattern already used by ExecutorFailedEvent:
Read from event.details instead of event.error
Extract details.message for the error text
Include details.extra context when available

* improve error handling consistency

python/packages/devui/agent_framework_devui/_mapper.py

@@ -840,7 +840,9 @@ class MessageMapper:
 
             if event_class == "WorkflowFailedEvent":
                 workflow_id = context.get("workflow_id", str(uuid4()))
-                error_info = getattr(event, "error", None)
+                # WorkflowFailedEvent uses 'details' field (WorkflowErrorDetails), not 'error'
+                # This matches ExecutorFailedEvent which also uses 'details'
+                details = getattr(event, "details", None)
 
                 # Import Response and ResponseError types
                 from openai.types.responses import Response, ResponseError
@@ -849,8 +851,14 @@ class MessageMapper:
                 request_obj = context.get("request")
                 model_name = request_obj.model if request_obj and request_obj.model else "devui"
 
-                # Create error object
-                error_message = str(error_info) if error_info else "Unknown error"
+                # Extract error message from WorkflowErrorDetails
+                if details:
+                    error_message = getattr(details, "message", None) or str(details)
+                    extra = getattr(details, "extra", None)
+                    if extra:
+                        error_message = f"{error_message} (extra: {extra})"
+                else:
+                    error_message = "Unknown error"
 
                 # Create ResponseError object (code must be one of the allowed values)
                 response_error = ResponseError(
@@ -945,7 +953,13 @@ class MessageMapper:
                 item_id = context.get(f"exec_item_{executor_id}", f"exec_{executor_id}_unknown")
                 # ExecutorFailedEvent uses 'details' field (WorkflowErrorDetails), not 'error'
                 details = getattr(event, "details", None)
-                err_msg: str | None = str(getattr(details, "message", details)) if details else None
+                if details:
+                    err_msg = getattr(details, "message", None) or str(details)
+                    extra = getattr(details, "extra", None)
+                    if extra:
+                        err_msg = f"{err_msg} (extra: {extra})"
+                else:
+                    err_msg = None
 
                 # Create ExecutorActionItem with failed status
                 executor_item = ExecutorActionItem(