curl --request POST \
  --url https://files-api.evolink.ai/api/v1/files/upload/base64 \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "base64_data": "data:image/png;base64,iVBORw0KGgo..."
}
'

{
  "success": true,
  "code": 200,
  "msg": "ファイルのアップロードに成功しました",
  "data": {
    "file_id": "file_abc123",
    "file_name": "avatar.png",
    "original_name": "avatar.png",
    "file_size": 2048,
    "mime_type": "image/png",
    "upload_path": "avatars",
    "file_url": "https://files.evolink.ai/avatars/avatar.png",
    "download_url": "https://files.evolink.ai/api/v1/files/download/file_abc123",
    "upload_time": "2025-10-09T00:00:00+08:00",
    "expires_at": "2025-10-12T00:00:00+08:00"
  }
}