fix: platform-aware delete confirmation + trial CTA to purchase

Delete subscription:
- Telegram mini app: native destructive popup (red button)
- Web (mobile + desktop): Sheet bottom panel with full-width buttons
- Both: proper loading state on delete button

Trial CTA: leads to /subscription/purchase (trial cannot be renewed)

src/components/subscription/PurchaseCTAButton.tsx

@@ -38,9 +38,12 @@ export default function PurchaseCTAButton({
         ? t('subscription.cta.renewHint', 'Продление подписки')
         : t('subscription.cta.activeHint');
 
-  // In multi-tariff mode: renew goes to per-subscription renew page
-  const linkTo =
-    isMultiTariff && subscription?.id
+  // Trial → purchase page (buy a real tariff, trial can't be renewed)
+  // Multi-tariff active → per-subscription renew page
+  // Otherwise → purchase page
+  const linkTo = isTrial
+    ? '/subscription/purchase'
+    : isMultiTariff && subscription?.id
       ? `/subscriptions/${subscription.id}/renew`
       : '/subscription/purchase';