format currency with thousand separators (#81)

src/lib/utils.ts

@@ -20,3 +20,12 @@ export function formatExpenseDate(date: Date) {
 export function formatCategoryForAIPrompt(category: Category) {
   return `"${category.grouping}/${category.name}" (ID: ${category.id})`
 }
+
+export function formatCurrency(currency: string, amount: number) {
+  const format = new Intl.NumberFormat('en-US', {
+    minimumFractionDigits: 2,
+    maximumFractionDigits: 2,
+  })
+  const formattedAmount = format.format(amount / 100)
+  return `${currency} ${formattedAmount}`
+}