Function calculate_advanced_spin_drift 

pub fn calculate_advanced_spin_drift(
    stability_factor: f64,
    time_of_flight_s: f64,
    _velocity_mps: f64,
    muzzle_velocity_mps: f64,
    _spin_rate_rad_s: f64,
    _caliber_m: f64,
    _mass_kg: f64,
    air_density_kg_m3: f64,
    is_right_twist: bool,
    _bullet_type: &str,
) -> f64

Calculate signed spin drift using the calibrated Litz total-drift fit.

The Litz 1.25 * (Sg + 1.2) * TOF^1.83 relation already fits total observed drift, including the effects of velocity loss and yaw damping. The additional state arguments are retained for API compatibility, but they must not be stacked onto the fitted total as independent multipliers. Atmospheric effects belong in the supplied stability_factor and time of flight. Muzzle velocity and density must remain finite and positive solely to preserve the legacy invalid-input contract; within that valid domain they do not rescale the result.