Open a source-of-funds record for a user. One per user per tenant.
curl https://api.geldstuck.com/v1/source-of-funds \ -H "x-api-key: $GELDSTUCK_PUBLIC_KEY" \ -H "x-api-secret: $GELDSTUCK_SECRET_KEY" \ -H "Content-Type: application/json" \ -d '{"userId": "usr_01HX3ZAB..."}'
{ "id": "sof_01HX3ZV...", "userId": "usr_01HX3ZAB...", "tenantId": "tnt_01HX3Z8MQW...", "status": "draft", "createdAt": "2026-04-22T11:00:00.000Z" }
status: "draft"