Function circular_orbital_period 

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

Computes the orbital period for a circular orbit.

Formula: T = 2π * sqrt(r^3 / (G * M))

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