refactor: organize backend by business responsibility

src/integrations/tbank/decimal.ts

@@ -0,0 +1,12 @@
+import { Decimal } from '../../common/decimal';
+
+const NANO = 1_000_000_000n;
+
+export type ProtoDecimal = { units?: string | number; nano?: string | number };
+
+export function decimal(value: ProtoDecimal): Decimal {
+  return {
+    value: BigInt(value.units ?? 0) * NANO + BigInt(value.nano ?? 0),
+    scale: 9,
+  };
+}