Embat ForeignExchangeRates API

`ForeignExchangeRate` records the daily exchange rates Embat uses to convert amounts between currencies for accounting purposes. Each record captures the rates observed on a given `date` for a set of currencies against a `baseCurrency` (EUR as stored).These are the same rates Embat applies internally when it computes exchange rates and accounting amounts on entities such as `Payment`, `Balance` and `Transaction`. Foreign exchange rates are read-only reference data: this API does not support creating, updating or deleting them.**Typical flow:** look up the rate for a given day to reproduce or audit a currency conversion made elsewhere in Embat.1. List the rates for a date range, optionally expressed against a currency other than EUR:```GET /foreignexchangerates?baseCurrency=USD&startDate=2024-01-01&endDate=2024-01-31```2. Or retrieve a single record you already know the `id` of, always expressed against EUR:```GET /foreignexchangerates/{id}```