[Feature]: Add Optional "name" Attribute (Per ag-ui Specification) to AguiMessage

With the increasing popularity of multi-agent collaboration scenarios, it is necessary to clearly identify which intelligent agent is performing tasks on the client side. To meet this requirement, we propose adding an optional "name" attribute to the AguiMessage component, which must comply with the ag-ui specification.

This "name" attribute is designed to carry the identifier of the intelligent agent. When multi-agent collaboration is in progress, the client can retrieve the value of this "name" attribute from AguiMessage and display it intuitively to the user, so that the user can clearly know which intelligent agent is currently working.

It should be emphasized that the "name" attribute is optional, which ensures backward compatibility with the existing usage of AguiMessage—existing scenarios that do not require multi-agent identification will not be affected.

[Write by AI]