Entry-point challenge: Quarto integration and output contracts in texreg

[leifeld]

This issue serves as an entry-point research challenge focused on the feasibility and design of Quarto integration for texreg.

Previous attempts and partial pull requests (see discussion under #190) suggest that this is not a straightforward implementation problem, but one that raises broader questions about output formats, rendering pipelines, and texreg's scope as reporting infrastructure.

The goal of this challenge is not necessarily to deliver a complete Quarto integration, but to clarify:

• what a principled Quarto integration would require;
• which parts should live in texreg versus in Quarto or extensions;
• whether texreg's current abstractions are sufficient or need revision;
• and which limitations or trade-offs are unavoidable.

Useful contributions may include:

• a design note analysing existing attempts and failure modes;
• a minimal prototype demonstrating one viable integration strategy;
• or a reasoned argument for why full integration is undesirable.

Partial exploration is entirely appropriate. There is no expectation that this challenge will result in a production-ready feature.

Please feel free to discuss the challenge or raise any questions either here or in a pull request if you decide to give it a try.