feat: add Lava payment provider support

- METHOD_LABELS entry for lava
- Custom SVG icon: dark base with orange-red lava flow and ember dots
- Admin settings tree node: payments_lava
- Locale strings (ru/en/zh/fa) for descriptions and admin labels

src/constants/paymentMethods.ts

@@ -22,6 +22,7 @@ export const METHOD_LABELS: Record<string, string> = {
   antilopay: 'Antilopay',
   jupiter: 'Jupiter',
   donut: 'Donut',
+  lava: 'Lava',
   apple_iap: 'Apple In-App Purchase',
   manual: 'Ручное пополнение',
 };