exchangeSettings.service/hook/card follow the backend's new shape: a
single ExchangeSettings object becomes a list, get() becomes list(),
and setFallbackRate(rate) becomes setFallbackRate(currency, rate).
ExchangeRateSettingsCard now renders one row per currency instead of
one hardcoded USD->ETB form.
manualPaymentSettings.service/hook/card add djfEnabled alongside
etb/usdEnabled, matching the backend's new column.
InvoicesPage's collected-summary KPI strip adds a DJF tile and folds
its ETB-equivalent into the existing 'Total collected' conversion,
reading each currency's rate from the now-list-shaped settings query.
Claude-Session: https://claude.ai/code/session_01CZy77vCWhka3pnmVF9NDkL
