List user DM channels

curl --request POST \
  --url https://api.fluxer.app/v1/admin/users/list-dm-channels \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "user_id": "<string>",
  "before": "<string>",
  "after": "<string>",
  "limit": 100
}
'

{
  "channels": [
    {
      "channel_id": "<string>",
      "channel_type": 1073741823,
      "recipient_ids": [
        "<string>"
      ],
      "last_message_id": "<string>",
      "is_open": true
    }
  ]
}