feat(freight-api): add DJF as a supported currency

Adds DJF to freight.payments_currency_enum (migration 3860000000000,
alone in its own migration per Postgres's ADD VALUE-in-a-transaction
restriction) and to manual_payment_settings (djf_enabled column,
migration 3870000000000, default true).

Replaces the binary ETB/USD assumptions that would have silently
mispriced or discarded a DJF booking:
- booking-pricing / contract-pricing: usdToEtb scalar -> a rate table
  keyed by source currency (ExchangeService.getRateTable), so a
  contract-frozen rate converts into whatever currency the booking is
  paid in instead of being dropped when neither leg is ETB or USD.
- warehouse-fee / booking-wagon-cancellation: normalizeCurrency no
  longer coerces anything non-ETB to USD.
- additional-charge: convertAmount no longer bails out for a currency
  that isn't literally ETB or USD.
- manual-payment-settings: isEnabled/enabledCurrencies cover DJF.

Widens the three @IsIn(['ETB','USD']) DTO validators, and adds DJF to
the export/report currency filter option lists.

Claude-Session: https://claude.ai/code/session_01CZy77vCWhka3pnmVF9NDkL

apps/edr-freight-api/src/modules/contracts/contract-pricing.service.ts

@@ -3,7 +3,7 @@ import { Injectable, UnprocessableEntityException } from '@nestjs/common';
 import { RatesService } from '../rule-engine/services/rates.service';
 import { ContainerTypesService } from '../rule-engine/services/container-types.service';
 import { round2 } from '../billing/invoice-settlement.util';
-import { ExchangeService } from '@edr/api-common';
+import { CurrencyCode, ExchangeService } from '@edr/api-common';
 import { ContractsRepository } from './contracts.repository';
 import { Contract } from './entities/contract.entity';
 
@@ -95,9 +95,9 @@ export class ContractPricingService {
       (r) => !r.shippingLineCompanyId,
     );
     const currency = contract.paymentCurrency;
-    const isEtb = currency === 'ETB';
-    const usdToEtb = isEtb ? await this.exchangeService.getRate('USD', 'ETB') : 1;
-    const convert = (usd: number): number => (isEtb ? round2(usd * usdToEtb) : usd);
+    const usdToTarget =
+      currency === 'USD' ? 1 : await this.exchangeService.getRate('USD', currency as CurrencyCode);
+    const convert = (usd: number): number => (currency === 'USD' ? usd : round2(usd * usdToTarget));
 
     const lineItems: ContractUnitRateLineItem[] = [];
     const baseType = this.baseRateType(contract);