Settle commercial identity nuances with consolidated enums and linking rules

Add commercial-identity-nuance-settlement.md resolving control_basis,
binding_trigger, cross-registry Synonymity strengths, OPI branch modeling,
escrow commitment type, reputation portability, payment edge cases, CRM renewal
rules, Person Account adapters, and eIDAS wallet scope. Update canon, OpenQuestions,
and all commercial-identity source notes.

research/commercial-identity/beneficial-ownership-kyc-boi.md

@@ -164,10 +164,14 @@ the target of a Beneficial Ownership Relationship — not a participation root.
 
 ## Open Questions
 
-- Standard `control_basis` enum across jurisdictions (US CDD vs. EU AMLD wording).
-- Whether BOI FinCEN ID should map to Registry Identifier or generic Identifier.
-- Modeling **exempt** legal entity customers (publicly traded, government) as
-  absence of BO relationship vs. explicit exemption Evidence.
+*(none — settled in `commercial-identity-nuance-settlement.md`)*
+
+## Settled
+
+- `control_basis` enum — jurisdiction-neutral role codes + `regulatory_basis`.
+- FinCEN ID → **Registry Identifier** on Natural Person.
+- Exempt entities → **Beneficial Ownership Exemption** Evidence (not absence).
+- BOI filing volatility separated from CDD Beneficial Ownership Relationships.
 
 ## References