eval tui

[mikasenghaas]

Description

Based on #734. Do not merge before.

This PR implements a live-updating TUI for multi-env logs (#734) using a opt-in --tui flag. This will be especially useful for large prod-scale evals with many envs. It is designed such that the default vf-eval is affected as little as possible. The only "structural" change is the introduction of the callback pattern into Environment.generate to handle per-env events (such as metric aggregation, logs, etc.).

uv run vf-eval configs/evals/debug.toml --tui

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Test improvement

Testing

• All existing tests pass when running uv run pytest locally.
• New tests have been added to cover the changes

Checklist

• My code follows the style guidelines of this project as outlined in AGENTS.md
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Additional Notes