fix: 修复大模型调用table_column_filter工具时解析llm json结果失败的问题

[RoverKai]

大模型使用deepseek，调用table_column_filter工具时会报错：

2025-10-21 20:05:00.529 | ERROR    | genie_tool.tool.table_rag.table_column_filter:_parse_json_result:201 - 生成结果格式不合法:{
    "relatedFlag": true,
    "columnIndexes": [1, 6, 7]
}，list index out of range
Traceback (most recent call last):
  File "/home/roverkai/Desktop/study/joyagent-jdgenie/genie-tool/genie_tool/tool/table_rag/table_column_filter.py", line 199, in _parse_json_result
    return result[0]
           ~~~~~~^^^
IndexError: list index out of range
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/home/roverkai/Desktop/study/joyagent-jdgenie/genie-tool/genie_tool/tool/table_rag/table_column_filter.py", line 234, in _filter_single_table
    result_dict = json.loads(self._parse_json_result(llm_response))
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/roverkai/Desktop/study/joyagent-jdgenie/genie-tool/genie_tool/tool/table_rag/table_column_filter.py", line 202, in _parse_json_result
    raise RuntimeError("解析llm json结果失败")
RuntimeError: 解析llm json结果失败
2025-10-21 20:05:00.531 | ERROR    | genie_tool.tool.table_rag.table_column_filter:_filter_single_table:260 - [filter column] 706bbb8c-352c-4e7a-914b-f4c130c533f1, fail to filter columns error_msg 第1次执行结果:
{
    "relatedFlag": true,
    "columnIndexes": [1, 6, 7]
}，报错信息:解析llm json结果失败

可以看到大模型并没有按规定输出

问题复现：点击「智能问数」菜单中的「分析产品的销售表现」按钮