feat: Prevent duplicate message processing in Nostr chat

- Add logic to track processed message IDs, ensuring that messages are not processed multiple times, which enhances the reliability of message handling in the chat component.

src/composables/useNostrChat.ts

@@ -417,6 +417,9 @@ export function useNostrChat() {
         pubkey: currentUser.value.pubkey
       }
 
+      // Add to processed IDs to prevent duplicate processing
+      processedMessageIds.value.add(event.id)
+
       if (!messages.value.has(peerPubkey)) {
         messages.value.set(peerPubkey, [])
       }