Function magnetic_force_on_moving_charge 

pub fn magnetic_force_on_moving_charge(
    charge: f64,
    velocity: f64,
    magnetic_flux_density: f64,
    angle_radians: f64,
) -> Option<f64>

Computes magnetic force using F = qvB sin(theta).

Returns None when any input is not finite or when the computed result is not finite.