Add commercial identity research corpus and binding concepts

Record deep research on commercial identity coupling across theory, law,
regulation, and software (KYC, LEI, DUNS, eIDAS, CRM). Introduce Commercial
Commitment, Legal Person, and Beneficial Owner to the canon model and document
the fluid-to-bound identity gradient in the conceptual model.

model/ConceptualModel.md

@@ -28,7 +28,9 @@ collapsing into `user`, `group`, or `tenant`.
 - Service Account: software-oriented account.
 - Identity Record: source-specific record about an actor or account.
 - Commercial Record: billing, CRM, or commerce-system record linked to an actor
-  or tenant (e.g., Stripe Customer).
+  or tenant (e.g., Stripe Customer, Salesforce Account).
+- Commercial Commitment: evidenced obligation binding commercial parties (contract,
+  subscription, payment mandate, regulated onboarding).
 - Profile: presentation or attribute surface.
 - Persona: contextual presentation of an actor.
 
@@ -75,7 +77,9 @@ Core relationship classes:
   scope.
 - Trust: actor, issuer, verifier, or system relies on another for a purpose.
 - Commercial: vendor actor provides services to customer actor; may reference a
-  Commercial Record for billing or subscription state.
+  Commercial Record and one or more Commercial Commitments.
+- Ownership (beneficial): natural person owns or controls organization customer
+  (KYC beneficial owner pattern).
 - Synonymity: records or identifiers are asserted to refer to the same target
   under stated evidence and scope.
 
@@ -201,6 +205,18 @@ revocation/supersession path via `Lifecycle State`.
 more `Tenant` scopes → `Representation Relationship` for authorized persons or
 agents.
 
+## Commercial Binding Gradient
+
+Identity representations vary in persistence based on commercial stake:
+
+- **Fluid**: no Commercial Commitment; personas and scoped identifiers may rotate
+  freely (low counterparty reliance).
+- **Bound**: Commercial Commitment + Evidence + often Commercial Record; identifiers
+  stabilize because counterparties bear risk (billing, contract, KYC, LEI).
+
+Commercial binding does not merge layers. It increases assurance requirements and
+lifecycle rigor on the records and relationships already in the model.
+
 ## Scenario Gaps
 
 No scenario requires glossary or principle changes that the current model
@@ -208,8 +224,7 @@ cannot satisfy. Remaining ambiguities are documented in `OpenQuestions.md`:
 
 - mandatory Synonymity Assertion field set;
 - Realm vs. Tenant promotion for Keycloak-heavy mappings;
-- Customer Account resolved: use Commercial Record + Commercial Relationship;
-  see `OpenQuestions.md`.
+- Beneficial Owner as dedicated relationship type vs. Ownership subtype.
 
 ## Invariants