Default component weights for the person-match score
default_weights.RdBase weights for each name/attribute field. The final contribution of a field
is weight * (2 * similarity - 1), so an identical field adds +weight, a
completely different field subtracts weight, and a missing field on either
side contributes 0 (neutral). The last_name weight is additionally scaled,
per pair, by a within-organization surname-rarity factor (see
surname_weight()): on a family-dominated board, agreement on the shared
surname carries almost no weight and the first name / suffix / gender do the
discriminating.