Deterministic blocked fuzzy matcher (greedy within block)
.bb_fuzzy_match(left, right, min_confidence = 0.92)data.frame: .block, left_id, right_id, match_method
(exact_name / fuzzy_jw / unmatched), match_confidence.
data.frames with columns .block, .id, .name_key
(and optional .jersey, .dob).
Jaro-Winkler similarity floor for a fuzzy match.