feat: ( payment ) implement cbe payment

apps/edr-payment-api/src/modules/cbe-bill/mappers/cbe-error.mapper.ts

@@ -0,0 +1,30 @@
+import { CbeFailureClass } from "../entities/cbe-bill-operation.entity";
+
+/**
+ * A CBE business/transport outcome we detected ourselves. `failureClass` drives the §6.5
+ * same-End_To_End_Txn_Id retry policy: BUSINESS outcomes are final (retrying cannot change
+ * the answer), TRANSIENT ones (our 5xx, domain app unreachable) may be retried by CBE.
+ */
+export class CbeBillError extends Error {
+  constructor(
+    message: string,
+    readonly failureClass: CbeFailureClass,
+  ) {
+    super(message);
+    this.name = "CbeBillError";
+  }
+}
+
+/**
+ * Every failure maps to Response_Code "3" — the AAFDA spec (§2.10, §3.10) defines only
+ * 0 (success), 1 (auth), 3 (business); only the description is specific (plan §6.6).
+ */
+export function toCbeFailure(err: unknown): {
+  description: string;
+  failureClass: CbeFailureClass;
+} {
+  if (err instanceof CbeBillError) {
+    return { description: err.message, failureClass: err.failureClass };
+  }
+  return { description: "Internal server error.", failureClass: "TRANSIENT" };
+}