Function run_cyclic_protocol 

pub fn run_cyclic_protocol(
    analysis: &mut Analysis,
    node: NodeId,
    dof: usize,
    tiers: &[(f64, usize)],
    step: f64,
    on_point: impl FnMut(f64, f64),
)

Runs a reverse-cyclic protocol: for each (amplitude, cycles) tier, in order, ramps 0 -> +amplitude -> -amplitude, cycles times, then back to 0 before the next tier. Calls on_point after every leg — this is the full recorded trace a stress-strain (or force-displacement) plot is built from.