fn neg(&self) -> Self {
        let [px, py, pz] = self.coordinates();
        // SAFETY:
        // - The negation formula for Edwards curves is well-defined.
        // - The result remains a valid curve point.
        let point = Self::new([-px, py.clone(), pz.clone()]);
        point.unwrap()
    }
Returns the additive inverse of the projective point `p`

# Safety

- Negating the x-coordinate of a valid Edwards point results in another valid point.
- `unwrap()` is safe because negation does not break the curve equation.
crates/math/src/elliptic_curve/edwards/point.rs