grok-3-mini 为思考模型，但引入了新的 usage 格式，completions_tokens  只统计非思考的回复内容长度： 
"usage": {
    "prompt_tokens": 32,
    "completion_tokens": 10,
    "total_tokens": 299,
    "prompt_tokens_details": {
      "text_tokens": 32,
      "audio_tokens": 0,
      "image_tokens": 0,
      "cached_tokens": 0
    },
    "completion_tokens_details": {
      "reasoning_tokens": 257,
      "audio_tokens": 0,
      "acce...