feat(frontend): add card-to-iban interface

frontend/app/utils/card.test.ts

@@ -0,0 +1,23 @@
+import { describe, expect, it } from 'vitest'
+
+import { formatCard, normalizeCard, validCard } from './card'
+
+describe('card utilities', () => {
+  it('normalizes Persian and Arabic digits with common separators', () => {
+    expect(normalizeCard('۶۰۳۷ ٩٩۷۵-۱۲۳۴ ۵۶۷۸')).toBe('6037997512345678')
+  })
+
+  it('keeps unexpected characters so validation can report them', () => {
+    expect(normalizeCard('6037 ABC 1234')).toBe('6037ABC1234')
+  })
+
+  it('accepts only sixteen ASCII digits', () => {
+    expect(validCard('6037997512345678')).toBe(true)
+    expect(validCard('603799751234567')).toBe(false)
+    expect(validCard('603799ABC2345678')).toBe(false)
+  })
+
+  it('groups a normalized card for display', () => {
+    expect(formatCard('6037997512345678')).toBe('6037 9975 1234 5678')
+  })
+})