- BuildContactEmailIndex: one-pass email→contact id map over all persons
(O(N) instead of per-address FindPersonByEmail O(N×M))
- BuildPersonOpportunityIndex: person→lowest-id opportunity for history notes
(OO has no person-level history; verified live)
- HistoryEntity{Opportunity,Case} whitelist constants
- IsCompany/ContactID/NumericIDLess/SortIDs helpers with unit tests