cli: wrap litellm_extra_body payload inside {"metadata": ... } in get_llm_extra_body()

Maintains previous structure expected by downstream, while still passing via litellm_extra_body (mapped to extra_body).

Co-authored-by: openhands <openhands@all-hands.dev>

openhands-cli/openhands_cli/utils.py

@@ -56,6 +56,7 @@ def get_llm_extra_body(
         metadata['session_id'] = session_id
     if user_id is not None:
         metadata['trace_user_id'] = user_id
+    metadata = {"metadata": metadata}
     return metadata