List LLM providers

{
  "llms": [
    {
      "id": 17,
      "name": "azure-gpt-4.1-mini",
      "provider_name": "azure",
      "is_premium": false,
      "service_type": "LLM",
      "is_active": true
    },
    {
      "id": 8,
      "name": "gemini-2.5-flash",
      "provider_name": "google",
      "is_premium": false,
      "service_type": "LLM",
      "is_active": true
    }
  ],
  "total": 13
}