fix: don't count unknown tool calls toward tool_call_count

pipeline_service/agent_loop_v2.py

@@ -185,6 +185,7 @@ class AgentExecutor:
                     }, ensure_ascii=False) + "\n"
 
                     result = await self._execute_tool(tool_name, tool_params)
+                    if not result.startswith("未知工具"):
                         self._tool_call_count += 1
 
                     yield json.dumps({