Function intersect_scopes 

pub fn intersect_scopes(
    a: &DelegationScope,
    b: &DelegationScope,
) -> DelegationScope

Computes the intersection of two scopes (intersection narrowing rule §9.6).

For each dimension:

• If either side is empty (wildcard), use the other side’s restriction
• Otherwise, take the set intersection
• For limits, take the most restrictive value