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);

apps/edr-freight-api/src/modules/contracts/dto/create-booking-request.dto.ts

@@ -98,7 +98,7 @@ export class CreateBookingRequestDto {
       'Billing currency for the shipment GL will book. Intercity is always ETB.',
   })
   @IsOptional()
-  @IsIn(['ETB', 'USD'])
+  @IsIn(['ETB', 'USD', 'DJF'])
   paymentCurrency?: string;
 
   @ApiPropertyOptional()

apps/edr-freight-api/src/modules/contracts/shipment-currency.spec.ts

@@ -20,7 +20,7 @@ const snapshot = (currency: string, unitPrice: number): ContractRateSnapshot =>
 const frozenByCode = (
   snap: ContractRateSnapshot | null,
   bookingCurrency: string,
-  usdToEtb: number,
+  fx: Record<string, number>,
 ): ContractRateSnapshot | null =>
   (
     BookingPricingService.prototype as unknown as {
@@ -28,14 +28,14 @@ const frozenByCode = (
         m: Map<string, ContractRateSnapshot> | null,
         code: string,
         bookingCurrency: string,
-        usdToEtb: number,
+        fx: Record<string, number>,
       ) => ContractRateSnapshot | null;
     }
   ).frozenRateByCode(
     snap ? new Map([['CONTAINER_20FT', snap]]) : null,
     'CONTAINER_20FT',
     bookingCurrency,
-    usdToEtb,
+    fx,
   );
 
 describe('per-shipment billing currency', () => {
@@ -61,25 +61,34 @@ describe('frozen contract rate in the booking currency', () => {
   it('converts a USD snapshot for an ETB booking instead of dropping it', () => {
     // The old behaviour returned null here, which silently re-priced the
     // booking at live rates and lost the agreed contract price.
-    expect(frozenByCode(snapshot('USD', 400), 'ETB', 150)?.unitPrice).toBe(60_000);
+    expect(frozenByCode(snapshot('USD', 400), 'ETB', { USD: 150 })?.unitPrice).toBe(60_000);
   });
 
   it('converts a grandfathered ETB snapshot back for a USD booking', () => {
-    expect(frozenByCode(snapshot('ETB', 60_000), 'USD', 150)?.unitPrice).toBe(400);
+    expect(frozenByCode(snapshot('ETB', 60_000), 'USD', { ETB: 1 / 150 })?.unitPrice).toBe(400);
+  });
+
+  it('converts a USD snapshot for a DJF booking via the USD->DJF rate', () => {
+    // 177.6 ETB/DJF pivot: USD->DJF = usdToEtb / djfToEtb = 150 / 0.845.
+    expect(frozenByCode(snapshot('USD', 400), 'DJF', { USD: 177.6 })?.unitPrice).toBe(71_040);
   });
 
   it('passes a matching-currency snapshot through untouched', () => {
     const snap = snapshot('USD', 400);
-    expect(frozenByCode(snap, 'USD', 1)).toBe(snap);
+    expect(frozenByCode(snap, 'USD', { USD: 1 })).toBe(snap);
   });
 
   it('refuses to price off an unusable exchange rate', () => {
     // Converting with 0 would zero the whole line.
-    expect(frozenByCode(snapshot('USD', 400), 'ETB', 0)).toBeNull();
-    expect(frozenByCode(snapshot('USD', 400), 'ETB', Number.NaN)).toBeNull();
+    expect(frozenByCode(snapshot('USD', 400), 'ETB', { USD: 0 })).toBeNull();
+    expect(frozenByCode(snapshot('USD', 400), 'ETB', { USD: Number.NaN })).toBeNull();
+  });
+
+  it('refuses to price off a currency the rate table has no entry for', () => {
+    expect(frozenByCode(snapshot('USD', 400), 'DJF', {})).toBeNull();
   });
 
   it('returns null when there is no snapshot', () => {
-    expect(frozenByCode(null, 'ETB', 150)).toBeNull();
+    expect(frozenByCode(null, 'ETB', { USD: 150 })).toBeNull();
   });
 });