Fix workflow transport

Author: dandavison

nexusmcp/workflow_transport.py

@@ -119,7 +119,7 @@ async def _handle_list_tools(self) -> types.ListToolsResult:
         return types.ListToolsResult(tools=tools)
 
     async def _handle_call_tool(self, params: types.CallToolRequestParams) -> types.CallToolResult:
-        service, _, operation = params.name.partition("/")
+        service, _, operation = params.name.partition("_")
         nexus_client = workflow.create_nexus_client(
             endpoint=self.endpoint,
             service=service,