Repository: promptfoo/promptfoo
Issue: Openai realtime api doesn't seem to support history.
Root cause: Validation Gap

**Describe the bug**

Passing messages history to realtime api doesn't seem to work at all (even in example from https://github.com/promptfoo/promptfoo/blob/main/examples/openai-realtime/promptfooconfig-conversation.yaml); realtime seems to ignore previous conversation.

**To Reproduce**
Steps to reproduce the behavior, including example Promptfoo configurations if applicable:

1) npx promptfoo@latest init --example openai-realtime
2) cd .\openai-realtime\
3) npx promptfoo eval -c promptfooconfig-conversation.yaml
4) Get result showing conversation doesn't seem to be propagated. 

![Image](https://github.com/user-attachments/assets/a93197ce-1772-401f-bfe9-b6d541ed93aa)

Looking at generated prompt field, it seems wrong (this is prompt from the 2nd turn of a sample conversation):

`[
  {
    "prompt": [
      {
        "role": "system",
        "content": [
          {
            "type": "input_text",
            "text": "You are a helpful, friendly AI assistant. Keep your responses conversational and engaging."
          }
        ]
      },
      {
        "role": "user",
        "content": [
          {
            "type": "input_text",
            "text": "What are some popular tourist destinations in Japan?"
          }
        ]
      }
    ],
    "input": [
      {
        "type": "input_text",
        "text": "What are some popular tourist destinations in Japan?"
      }
    ],
    "output": "Some popular tourist destinations in Japan include:\n\n1. Tokyo - The bustling capital city known for its modern architecture, shopping districts, and cultural landmarks like the Meiji Shrine and Tokyo Tower.\n2. Kyoto - Famous for its well-preserved temples, traditional wooden houses, and beautiful gardens, including the Fushimi Inari Shrine and Kinkaku-ji (Golden Pavilion).\n3. Osaka - Known for its vibrant nightlife, street food, and attractions like Osaka Castle and Universal Studios Japan.\n4. Hiroshima - Home to the Peace Memorial Park and Museum, and the iconic Itsukushima Shrine on Miyajima Island.\n5. Nara - Renowned for its historic temples like Todai-ji, famous for its giant Buddha statue, and friendly deer roaming in Nara Park.\n6. Mount Fuji - Japan's highest peak, offering stunning views and popular hiking trails.\n7. Hokkaido - Known for its natural beauty, ski resorts, and national parks like Shiretoko and Daisetsuzan.\n8. Okinawa - A group of tropical islands known for their beautiful beaches, coral reefs, and unique Ryukyuan culture."
  },
  {
    "prompt": [
      {
        "role": "system",
        "content": [
          {
            "type": "input_text",
            "text": "You are a helpful, friendly AI assistant. Keep your responses conversational and engaging."
          }
        ]
      },
      {
        "role": "user",
        "content": [
          {
            "type": "input_text",
            "text": [
              {
                "type": "input_text",
                "text": "What are some popular tourist destinations in Japan?"
              }
            ]
          }
        ]
      },
      {
        "role": "assistant",
        "content": [
          {
            "type": "text",
            "text": "Some popular tourist destinations in Japan include:\n\n1. Tokyo - The bustling capital city known for its modern architecture, shopping districts, and cultural landmarks like the Meiji Shrine and Tokyo Tower.\n2. Kyoto - Famous for its well-preserved temples, traditional wooden houses, and beautiful gardens, including the Fushimi Inari Shrine and Kinkaku-ji (Golden Pavilion).\n3. Osaka - Known for its vibrant nightlife, street food, and attractions like Osaka Castle and Universal Studios Japan.\n4. Hiroshima - Home to the Peace Memorial Park and Museum, and the iconic Itsukushima Shrine on Miyajima Island.\n5. Nara - Renowned for its historic temples like Todai-ji, famous for its giant Buddha statue, and friendly deer roaming in Nara Park.\n6. Mount Fuji - Japan's highest peak, offering stunning views and popular hiking trails.\n7. Hokkaido - Known for its natural beauty, ski resorts, and national parks like Shiretoko and Daisetsuzan.\n8. Okinawa - A group of tropical islands known for their beautiful beaches, coral reefs, and unique Ryukyuan culture."
          }
        ]
      },
      {
        "role": "user",
        "content": [
          {
            "type": "input_text",
            "text": "Which of those places is best to visit in autumn?"
          }
        ]
      }
    ],
    "input": [
      {
        "type": "input_text",
        "text": "Which of those places is best to visit in autumn?"
      }
    ],
    "output": "Some great places to visit in autumn include:\n\n1. New England in the USA for its stunning fall foliage.\n2. Kyoto, Japan, known for its beautiful autumn leaves.\n3. Bavaria, Germany, where you can experience traditional Oktoberfest celebrations.\n4. Tuscany, Italy, for its picturesque landscapes and harvest season.\n5. The Canadian Rockies, offering breathtaking scenery and fewer crowds.\n\nEach of these destinations offers something special during the autumn season."
  }
]`

**Expected behavior**
Openai can continue the conversation.

**Screenshots**
If applicable, add screenshots to help explain your problem.

**System information:**

If possible, please output the results of `promptfoo debug` and paste the output here.

- Promptfoo version: 0.107.4

**Additional context**

The similar behavior is present when I'm trying to write my tests (that include conversation so far)