RumBugen/sevdesk-api-kotlin — reverse-engineered prompt

Build me a simple Kotlin client library for the SevDesk REST API that feels easy to use from another app. I mainly want the parts that are already shown as supported in the README to work well, especially bookkeeping system version, check accounts, check account transactions, contacts, contact addresses, communication ways, and contact fields including their settings. It should make the common actions straightforward, like listing records, creating new ones, getting a single item by id, updating it, deleting it, and handling special actions like balance lookups or enshrining transactions where that already exists.

Please keep the models and method names clean and consistent, add a simple way to pass the SevDesk API token, and return useful errors instead of vague failures. I would also like a short README with a few copy paste examples so someone can quickly connect and make real requests. For endpoints that are not implemented yet, do not fake them, just leave clear TODOs or obvious gaps. Look up the current SevDesk docs online if you need exact request details.