fix: support 100% discount display + fix Telegram link widget race condition

- formatPrice shows "Бесплатно/Free" when price is 0 (SubscriptionPurchase, Subscription, RenewSubscription)
- Add subscription.free locale key (ru/en/zh/fa)
- Fix TelegramLinkWidget NS_BINDING_ABORTED: move legacy widget callback to ref pattern, remove unstable deps (showToast, t, navigate) from useEffect — prevents iframe destruction on re-render
- Clean up OIDC effect deps

src/pages/RenewSubscription.tsx

@@ -177,7 +177,9 @@ export default function RenewSubscription() {
                   </div>
                   <div className="text-right">
                     <div className="text-base font-semibold" style={{ color: g.text }}>
-                      {formatAmount(option.price_kopeks / 100)} {currencySymbol}
+                      {option.price_kopeks === 0
+                        ? t('subscription.free', 'Бесплатно')
+                        : `${formatAmount(option.price_kopeks / 100)} ${currencySymbol}`}
                     </div>
                     {months > 1 && (
                       <div className="text-[11px]" style={{ color: g.textSecondary }}>