Function lorentz_force_magnitude_perpendicular 

pub fn lorentz_force_magnitude_perpendicular(
    charge: f64,
    electric_field_magnitude: f64,
    speed: f64,
    magnetic_flux_density_magnitude: f64,
) -> Option<f64>

Computes |F| = |q| * |E + vB| for perpendicular fields along the same scalar direction.

Returns None when speed is negative, when either field magnitude is negative, when any input is not finite, or when the computed result is not finite.