implement exchange settings management and fallback rate handling

apps/edr-freight-api/src/modules/exchange-settings/exchange-settings.module.ts

@@ -0,0 +1,20 @@
+import { Global, Module } from "@nestjs/common";
+import { TypeOrmModule } from "@nestjs/typeorm";
+
+import { ExchangeSetting } from "./entities/exchange-setting.entity";
+import { ExchangeSettingsController } from "./exchange-settings.controller";
+import { ExchangeSettingsService } from "./exchange-settings.service";
+
+/**
+ * Global so the several `ExchangeModule.forRootAsync` registrations (bookings,
+ * contracts, warehouses) can inject {@link ExchangeSettingsService} into their
+ * options factory without each importing this module.
+ */
+@Global()
+@Module({
+  imports: [TypeOrmModule.forFeature([ExchangeSetting])],
+  controllers: [ExchangeSettingsController],
+  providers: [ExchangeSettingsService],
+  exports: [ExchangeSettingsService],
+})
+export class ExchangeSettingsModule {}