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/payment/entities/payment.entity.ts

@@ -5,7 +5,7 @@ import { PaymentRefundEntity } from "./payment-refund.entity";
 /** Invoice source that owns the intent ('booking', 'demurrage', …) — caller-supplied. */
 type PaymentType = string
 type PaymentMethod = "telebirr" | "cbe-birr" | "ebirr" | "waafi" | "card" | "dmoney" | "cac-bank" | "cbe-bill"
-type Currency = "ETB" | "USD"
+type Currency = "ETB" | "USD" | "DJF"
 export type PaymentStatus = "action-required" | "processing" | "success" | "failed" | "canceled" | "refunded"
 
 @Entity({ schema: 'freight', name: 'payments' })
@@ -25,7 +25,7 @@ export class PaymentEntity extends BaseEntity {
     @Column({ type: "enum", enum: ["telebirr", "cbe-birr", "ebirr", "waafi", "card", "dmoney", "cac-bank", "cbe-bill"] })
     method!: PaymentMethod
 
-    @Column({ type: "enum", enum: ["ETB", "USD"] })
+    @Column({ type: "enum", enum: ["ETB", "USD", "DJF"] })
     currency!: Currency
 
     @Column({ type: "numeric" })