Add small SaaS profile proof

infospace/profiles/small-saas/artifacts/dataset.subscription-ledger.yaml

@@ -0,0 +1,21 @@
+id: small-saas/dataset/subscription-ledger
+kind: dataset
+title: Subscription Ledger Dataset
+profile: small-saas
+owner_service: small-saas/service/billing-portal
+classification: customer-confidential
+tenant_scope: per-tenant
+tenant_ids:
+  - small-saas/tenant/acme
+  - small-saas/tenant/globex
+evidence_ids:
+  - small-saas/evidence/access-review-2026-05
+relationships:
+  - type: owned_by
+    target: small-saas/service/billing-portal
+  - type: partitioned_for
+    target: small-saas/tenant/acme
+  - type: partitioned_for
+    target: small-saas/tenant/globex
+  - type: governed_by
+    target: small-saas/policy/tenant-isolation