Add small SaaS profile proof

infospace/profiles/small-saas/artifacts/service.billing-portal.yaml

@@ -0,0 +1,28 @@
+id: small-saas/service/billing-portal
+kind: service
+title: Billing Portal Service
+profile: small-saas
+system_id: small-saas/system/billing-system
+owner_team: small-saas/team/platform
+runtime_deployment: small-saas/deployment/production
+datasets:
+  - small-saas/dataset/subscription-ledger
+controls:
+  - small-saas/control/namespace-per-tenant
+policies:
+  - small-saas/policy/tenant-isolation
+evidence_ids:
+  - small-saas/evidence/access-review-2026-05
+relationships:
+  - type: part_of
+    target: small-saas/system/billing-system
+  - type: owned_by
+    target: small-saas/team/platform
+  - type: stores
+    target: small-saas/dataset/subscription-ledger
+  - type: deployed_as
+    target: small-saas/deployment/production
+  - type: governed_by
+    target: small-saas/policy/tenant-isolation
+  - type: protected_by
+    target: small-saas/control/namespace-per-tenant