Connect customer quotations and payment execution to Sendico (#50)

frontend/packages/sxchnge_wallet/README.md

@@ -32,8 +32,9 @@ wallet state changes. The adapter reuses the KYC package's limit DTO and mapper.
 
 ## Integration boundary
 
-Replace `WalletService` and `LimitsService` together with authenticated backend
-adapters. The backend must provide authorization, authoritative quotes/balances,
+Backend mode now uses `BackendWalletService` and `WalletFactorService` with the
+authenticated BFF; `BackendLimitsService` supplies the reviewed platform projection.
+See [payment provisioning and rollout](../../../docs/payments.md). The backend must provide authorization, authoritative quotes/balances,
 atomic limits enforcement, durable idempotency and operation reconciliation.
 Add supported payment methods and validated recipients from that contract, rather
 than interpreting the demo input as production bank validation. Replace profile