reconsider prompt delimiters construction

[choccccy]

Right now, prompts get somewhat malformed, missing several newlines. In a commit that's coming soon:tm:, i'll be hardcoding the templates in pylib/prompting/model_style.py, but obviously a solution that can programmatically add lines more intelligently would be cool.

[choccccy]

while this has been solved for prompting templates that are already included, I want to keep this ticket open until we have a more robust solution for different prompting styles