fix(rates): render stored rate currency, default last mile to birr

The rate matrix currency cell hardcoded USD, so a last-mile rate
priced in ETB still displayed as dollars. formatCell now takes the
row and reads its currency code, falling back to USD.

Last-mile currency select gets defaultValue ETB (new generic
FormFieldDef.defaultValue for create-time pre-selection) and lists
ETB (Birr) first; USD stays selectable. Backend already persisted
and validated the chosen currency.

apps/edr-freight-web/backoffice/src/components/ruleEngine/ruleEngineFormat.tsx

@@ -17,7 +17,13 @@ const extractLabel = (value: unknown): string | null => {
   );
 };
 
-export const formatCell = (value: unknown, format?: ColumnFormat): ReactNode => {
+export const formatCell = (
+  value: unknown,
+  format?: ColumnFormat,
+  // The row the cell came from — currency amounts read their code off it so a
+  // last-mile rate priced in birr does not render as USD.
+  row?: Record<string, unknown>,
+): ReactNode => {
   if (value === null || value === undefined || value === "") {
     return <Text size="sm" c="dimmed">—</Text>;
   }
@@ -109,9 +115,10 @@ export const formatCell = (value: unknown, format?: ColumnFormat): ReactNode =>
 
   if (format === "currency") {
     const num = Number(value);
+    const code = typeof row?.currency === "string" ? row.currency : "USD";
     return (
       <Text size="sm" fw={500}>
-        {Number.isNaN(num) ? String(value) : `USD ${num.toLocaleString()}`}
+        {Number.isNaN(num) ? String(value) : `${code} ${num.toLocaleString()}`}
       </Text>
     );
   }