fix structured output pretty formatting

[Chris Ruppelt (Cruppelt)]

The current formatter is missing results for structured outputs in a trace's messages. - JSON_REDACTED section.

[
  {
    "role": "system",
    "content": "REDACTED"
  },
  {
    "role": "user",
    "content": "REDACTED"
  },
  {
    "id": [
      "langchain",
      "schema",
      "messages",
      "AIMessage"
    ],
    "kwargs": {
      "additional_kwargs": {
        "parsed": {
          "id": [
            "REDACTED"
          ],
          "lc": 1,
          "repr": "REDACTED",
          "type": "not_implemented"
        }
      },
      "content": [
        {
          "id": "REDACTED",
          "summary": [],
          "type": "reasoning"
        },
        {
          "annotations": [],
          "id": "msg_04c525be8d882ab3006977dc64cc948197802fba31a5351d60",
          "text": "JSON_REDACTED",
          "type": "text"
        }
      ],
      "id": "resp_04c525be8d882ab3006977dc613a10819799343c18e4771890",
      "invalid_tool_calls": [],
      "response_metadata": {
        "created_at": 1769462881.0,
        "id": "resp_04c525be8d882ab3006977dc613a10819799343c18e4771890",
        "metadata": {},
        "model": "gpt-5-mini-2025-08-07",
        "model_name": "gpt-5-mini-2025-08-07",
        "model_provider": "openai",
        "object": "response",
        "service_tier": "default",
        "status": "completed"
      },
      "tool_calls": [],
      "type": "ai",
      "usage_metadata": {
        "input_token_details": {
          "cache_read": 0
        },
        "input_tokens": 3860,
        "output_token_details": {
          "reasoning": 192
        },
        "output_tokens": 408,
        "total_tokens": 4268
      }
    },
    "lc": 1,
    "type": "constructor"
  }
]