Function circular_orbital_velocity 

pub fn circular_orbital_velocity(
    source_mass: f64,
    orbital_radius: f64,
) -> Option<f64>

Computes the circular orbital velocity around a source mass.

Formula: v = sqrt(G * M / r)

Returns None when source_mass is negative, when orbital_radius is less than or equal to zero, or when the computed result is not finite.