Function run_optimization_loop 

pub fn run_optimization_loop(
    scores: &[f64],
    max_iterations: u32,
    target_threshold: f64,
) -> (u32, f64)

Run the core optimization loop with injectable evaluation and proposal functions.

This is the pure logic extracted for testability. Given a sequence of scores (one per iteration, plus the initial score), it runs the loop respecting max_iterations and target_threshold.

Returns (iterations_run, best_score).