Change auto indentation rules

<img width="573" height="146" alt="Image" src="https://github.com/user-attachments/assets/837d05a3-255c-458a-af9f-897fb4151e56" />

Marijn gave some pointers here https://discuss.codemirror.net/t/custom-language-default-behaviour-of-auto-indentation-without-configuration/9412/3