feat: voucher crud and list

tests/vouchers-validate.test.ts

@@ -0,0 +1,12 @@
+import { describe, it, expect } from "vitest";
+import { validateVoucher, formatEuro } from "../lib/vouchers";
+describe("validateVoucher", () => {
+  it("lehnt negativen Rest und Rest über Wert ab", () => {
+    const base = { name: "X", anbieter: "Y", wertCents: 5000, restCents: 6000, ablaufdatum: null };
+    expect(validateVoucher(base)).toContain("restCents");
+    expect(validateVoucher({ ...base, restCents: -1 })).toContain("restCents");
+  });
+  it("formatEuro zeigt 25,50 €", () => {
+    expect(formatEuro(2550)).toContain("25,50");
+  });
+});