implement exchange settings management and fallback rate handling

apps/edr-freight-api/src/modules/contracts/contracts.module.ts

@@ -1,9 +1,8 @@
 import { Module, forwardRef } from '@nestjs/common';
 import { UserTradeAccessModule } from '../user-trade-access/user-trade-access.module';
-import { ConfigService } from '@nestjs/config';
 import { TypeOrmModule } from '@nestjs/typeorm';
-import { ExchangeModule, ExchangeOptions } from '@edr/api-common';
 
+import { registerExchangeModule } from '../exchange-settings/exchange-module-options';
 import { BillingModule } from '../billing/billing.module';
 import { CompaniesModule } from '../companies/companies.module';
 import { FilesModule } from '../files/files.module';
@@ -102,11 +101,7 @@ import { ContractDocumentViewModelBuilder } from '../../contracts/contract-docum
     // by ContractBookingService.createUnderContract. forwardRef because
     // TrainSchedulingModule already imports ContractsModule.
     forwardRef(() => TrainSchedulingModule),
-    ExchangeModule.forRootAsync({
-      inject: [ConfigService],
-      useFactory: (config: ConfigService): ExchangeOptions =>
-        config.get<ExchangeOptions>('app.cbeExchange') ?? {},
-    }),
+    registerExchangeModule(),
   ],
   controllers: [ContractsController, GlExchangeController],
   providers: [