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
