List saved AI providers

[
  {
    "managed": true,
    "id": "<string>",
    "label": "<string>",
    "provider": "openai",
    "model": "<string>",
    "baseURL": "<string>",
    "enabled": true,
    "isDefault": true,
    "testStatus": "<string>",
    "testError": "<string>",
    "apiKeyPreview": "<string>",
    "apiKeyFingerprint": "<string>",
    "lastTestedAt": "2026-08-10T12:00:00Z",
    "lastUsedAt": "2026-08-10T12:00:00Z",
    "createdAt": "2026-08-10T12:00:00Z",
    "updatedAt": "2026-08-10T12:00:00Z"
  }
]

{
  "defined": true,
  "code": "PRECONDITION_FAILED",
  "status": 412,
  "message": "AI providers aren't available on this server. Ask the server administrator to set ENCRYPTION_SECRET.",
  "data": null
}

{
  "defined": true,
  "code": "<string>",
  "status": 1,
  "message": "<string>",
  "data": null
}