Add ifeval_pt to harness

[Nkluge-correa]

This PR introduces a Portuguese variant of the original ifeval task (i.e., ifeval_pt).

Because adapting ifeval required changes to some supporting scripts, we decided (for this initial PR) to keep the Portuguese variant separate from the existing implementation. Our goal is to make it easier for maintainers to review the changes and decide on the most appropriate integration strategy (e.g., keeping it as a standalone task or incorporating it into a multilingual version with refactored supporting scripts).

The dataset and metadata were manually translated by our team, which includes native Portuguese speakers. We also carefully reviewed the resulting evaluation outputs to ensure the correctness and consistency of the task. Results obtained using this evaluation are reported in our paper: https://arxiv.org/abs/2603.03543.

Note: We are also preparing additional Portuguese evaluations (including GSM8K and RULER variants), which we plan to submit in separate PRs.

[Nkluge-correa]

Hello!
Is there anything still missing from this PR for it to be reviewed and considered? I have a few additional tasks I’d like to officially add to the harness, but I want to avoid overwhelming the maintainers with multiple PRs. I’m holding off on opening more until this one is resolved, so we can tackle things one at a time.