Function specificity_score 

pub fn specificity_score(shape: &'static Shape) -> u64

Compute a specificity score for a shape. Lower score = more specific.

This is used to disambiguate when a value could satisfy multiple types. For example, the value 42 fits both u8 and u16, but u8 is more specific (lower score), so it should be preferred. Compute a specificity score for a shape.

Lower score = more specific type. Used for type-based disambiguation where we want to try more specific types first (e.g., u8 before u16).