feat(payment-providers): implement Waafi in provider package

packages/types/src/common/payments.ts

@@ -42,6 +42,12 @@ export interface ProviderInitiationInput {
   amountMinor: number;
   currency: string;
   platform?: PaymentPlatform;
+  /**
+   * Payer account identifier (e.g. mobile-wallet MSISDN in full international format).
+   * Optional and provider-specific: some wallet providers (e.g. Waafi HPP with
+   * MWALLET_ACCOUNT) require the payer's phone number up front to pre-fill the hosted page.
+   */
+  payerAccount?: string;
 }
 
 export interface ProviderInitiationResult {