feat: 新增agent接口

Yi.Abp.Net8/module/ai-hub/Yi.Framework.AiHub.Domain/Mcp/OnlineSearchTool.cs

@@ -8,8 +8,8 @@ namespace Yi.Framework.AiHub.Domain.Mcp;
 public class OnlineSearchTool:ISingletonDependency
 {
     [McpServerTool, Description("进行在线搜索")]
-    public void OnlineSearch()
+    public string OnlineSearch(string keyword)
     {
-        
+        return "xxx";
     }
 }