feat: add Apple IAP (apple_iap) payment method support

Add apple_iap across all payment surfaces: method label, icon (Apple
logo SVG), admin settings tree (APPLE_IAP category), and all four
locale files (en, ru, fa, zh) with payment description + tree label.

src/components/admin/constants.ts

@@ -55,6 +55,7 @@ export const SETTINGS_TREE: SettingsTreeConfig = {
         { id: 'payments_paypear', categories: ['PAYPEAR'] },
         { id: 'payments_rollypay', categories: ['ROLLYPAY'] },
         { id: 'payments_aurapay', categories: ['AURAPAY'] },
+        { id: 'payments_apple_iap', categories: ['APPLE_IAP'] },
       ],
     },
     {