Function run_tournament 

pub fn run_tournament(
    hypotheses: Vec<Hypothesis>,
    config: &TournamentConfig,
    repo_root: &Path,
) -> Vec<HypothesisResult>

Run a tournament: evaluate all hypotheses in parallel sandboxes, sort by fitness, return ranked results.

In the async version, this would use tokio::spawn + Semaphore. For now, we use a thread pool approach.