Function step 

pub fn step(
    peds: &mut [Pedestrian],
    walls: &[WallSegment],
    params: &Params,
    dt: f64,
)

👎Deprecated since 0.0.3:

O(n²) reference path with per-tick heap allocation; use step_scratch (zero-alloc) or step_with_grid (broadphase) instead. See docs/rustsim-crowd.md P1-7.

Free-function step for callers that do not need trait dispatch.

Deprecated. O(n²) reference path with per-tick heap allocation. Use step_scratch (zero-alloc) or step_with_grid (broadphase) in production. Retained for parity tests and back-compat.

dt is the duration represented by a single step; it drives stride length as v * dt but is otherwise unused (the model is kinematic).