chutoro-core also ships scalar Euclidean and cosine distance helpers. Both
validate inputs for finite values, matching dimensions, and positive lengths
before computing the distance. The functions return the Distance newtype,
which dereferences to f32 and exposes the raw value through value().
Use CosineNorms::from_vectors or CosineNorms::new to pre-compute validated
L2 norms for cosine distance. Reuse the cached norms across repeated queries to
avoid redundant work; the cosine helper verifies cached values before it
performs the final calculation.