Python: [BREAKING] Fix #3613 chat/agent message typing alignment (#3920)

* Fix #3613 message typing across chat and agents

* Address #3613 review feedback and sample input style

* refactor: use shared AgentRunMessages aliases (#3613)

* refactor: rename agent run input aliases for #3613

* samples: inline image content in run calls

* core: export AgentRunInputs from package init

* core: use explicit init re-exports without __all__

* updated logging and inits

* Fix core mypy export and samples XML note

* Remove AgentRunInputsOrNone and dedupe loggers

* Remove prepare_messages helper

* fix integration tests

python/packages/ag-ui/getting_started/client.py

@@ -11,7 +11,7 @@ import asyncio
 import os
 from typing import cast
 
-from agent_framework import ChatResponse, ChatResponseUpdate, ResponseStream
+from agent_framework import ChatResponse, ChatResponseUpdate, Message, ResponseStream
 from agent_framework.ag_ui import AGUIChatClient
 
 
@@ -44,7 +44,7 @@ async def main():
                 metadata = {"thread_id": thread_id} if thread_id else None
 
                 stream = client.get_response(
-                    message,
+                    [Message(role="user", text=message)],
                     stream=True,
                     options={"metadata": metadata} if metadata else None,
                 )