fix(storefront): polish cart

Fix real regression: the payment success checkmark and timeout clock
icons had been corrupted to literal '?' glyphs (confirmed via git
history — ✓ and ⏱ were replaced), so a customer who just paid saw a
confusing '?' instead of a success indicator. Restored both icons and
marked them aria-hidden since the adjacent heading already conveys
the status.

Add missing accessible names to icon-only buttons that had none:
quantity increase/decrease controls and the mobile delete button
(desktop remove button had a title attribute only, which is not
reliably announced by screen readers — added aria-label alongside it).
New cart.increaseQuantity/decreaseQuantity keys added across all
three locales.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/i18n/translations.ts

@@ -103,6 +103,8 @@ export interface Translations {
     autoClose: string;
     confirmClear: string;
     removeItem: string;
+    increaseQuantity: string;
+    decreaseQuantity: string;
     paymentQrAlt: string;
     acceptTerms: string;
     copyError: string;