create_or_edit_existing: starts with avatar dashboard if user has any avatarscreate: starts with avatar creation flow regardless avatar existence;edit_existing: starts with editor for avatar with provided id.session_id to distinguish webhook events between multiple sessions.curl --location --request POST 'http://dev-cn.your-api-server.com/api/v1/sessions/new' \
--header 'Content-Type: application/json' \
--data-raw '{
"user_id": "<put-user-id-here>",
"config": {
"type": "create_or_edit_existing"
}
}'{
"url": "string",
"id": "497f6eca-6276-4993-bfeb-53cbbbba6f08",
"custom_upload_url": "string"
}