fix: improve currency regex and split membership gift types for better tracking

shared/chat.ts

@@ -22,5 +22,6 @@ export type ChatMessage = {
   isVerified?: boolean;
   superChat?: SuperChatInfo;
   membershipGift?: boolean;
+  membershipGiftPurchase?: boolean;
   membershipLevel?: string; // e.g., "New member", "Member (6 months)", etc.
 };