Function validate_push_vs_pull 

pub fn validate_push_vs_pull(
    push_wip: f64,
    push_throughput: f64,
    push_cycle_time: f64,
    pull_wip: f64,
    pull_throughput: f64,
    pull_cycle_time: f64,
    throughput_tolerance: f64,
) -> Result<TpsTestResult, String>

Validates Push vs Pull system performance.

TC-1: Pull (CONWIP) achieves better cycle time with similar throughput

Errors

This function always returns Ok. The Result type is for consistency.