Function born_probability 

pub fn born_probability<R>(
    state: &HilbertState<R>,
    basis: &HilbertState<R>,
) -> PropagatingEffect<R>
where
    R: RealField + FromPrimitive + Sum + Default + Debug,

Causal wrapper for mechanics::born_probability_kernel.

The kernel validates and clamps the probability to [0, 1], so the value channel carries the plain real directly.