Exchange rate providers are now pluggable via the module Registry. The four built-in drivers (currency_converter, currency_freak, currency_layer, open_exchange_rate) move from a static config array into App\\Providers\\DriverRegistryProvider, which calls Registry::registerExchangeRateDriver() for each during app boot with metadata the frontend needs: label (i18n key), website (help-text URL), and config_fields (schema for driver-specific driver_config JSON).
The Currency Converter's server-type selector and dedicated URL field — previously hardcoded in ExchangeRateProviderModal.vue — are now just another config_fields entry with a visible_when rule that shows the URL input only when type=DEDICATED. Any module that wants to ship a custom driver gets the same treatment for free: declare config_fields in the registration, and the host app's modal renders them automatically.
ExchangeRateDriverFactory::make() falls back to Registry::driverMeta() when a name isn't in the local built-in map, and availableDrivers() merges both sources. ConfigController handles the exchange_rate_drivers key specially by mapping Registry::allDrivers('exchange_rate') to enriched option objects, so the config-file route still works for every other key. The static exchange_rate_drivers + currency_converter_servers arrays in config/invoiceshelf.php are deleted.
Unit tests cover the new Registry::register/flushDrivers, the factory merging built-ins with Registry-contributed drivers, and the factory rejecting unknown names. A feature test exercises the end-to-end /api/v1/config?key=exchange_rate_drivers response shape.
NOTE: this commit depends on invoiceshelf/modules package commit e44d951 which adds the Registry driver API. The package needs to be released and pinned in composer.json before a fresh composer install on this commit will work.
Darko Gjorgjijoski