Fix UI not updating for delivery status changes

- Use message ID instead of index for ForEach to trigger proper updates
- Add explicit objectWillChange.send() when updating delivery status
- Fix scroll-to-bottom logic to use message IDs
- This should make blue checkmarks appear when read receipts are received

bitchat/ViewModels/ChatViewModel.swift

@@ -2142,6 +2142,11 @@ extension ChatViewModel: BitchatDelegate {
                 chatMessages[index] = updatedMessage
                 privateChats[peerID] = chatMessages
                 print("[Delivery] Updated message in private chat with \(peerID)")
+                
+                // Force UI update by triggering objectWillChange
+                DispatchQueue.main.async { [weak self] in
+                    self?.objectWillChange.send()
+                }
             }
         }
         
@@ -2152,6 +2157,11 @@ extension ChatViewModel: BitchatDelegate {
                 updatedMessage.deliveryStatus = status
                 roomMsgs[index] = updatedMessage
                 roomMessages[room] = roomMsgs
+                
+                // Force UI update
+                DispatchQueue.main.async { [weak self] in
+                    self?.objectWillChange.send()
+                }
             }
         }
     }

bitchat/Views/ContentView.swift

@@ -439,7 +439,7 @@ struct ContentView: View {
                         }
                     }()
                     
-                    ForEach(Array(messages.enumerated()), id: \.offset) { index, message in
+                    ForEach(messages, id: \.id) { message in
                         VStack(alignment: .leading, spacing: 4) {
                             // Check if current user is mentioned
                             let isMentioned = message.mentions?.contains(viewModel.nickname) ?? false
@@ -505,16 +505,16 @@ struct ContentView: View {
                         }
                         .padding(.horizontal, 12)
                         .padding(.vertical, 2)
-                        .id(index)
+                        .id(message.id)
                     }
                 }
                 .padding(.vertical, 8)
             }
             .background(backgroundColor)
             .onChange(of: viewModel.messages.count) { _ in
-                if viewModel.selectedPrivateChatPeer == nil {
+                if viewModel.selectedPrivateChatPeer == nil && !viewModel.messages.isEmpty {
                     withAnimation {
-                        proxy.scrollTo(viewModel.messages.count - 1, anchor: .bottom)
+                        proxy.scrollTo(viewModel.messages.last?.id, anchor: .bottom)
                     }
                 }
             }
@@ -523,7 +523,7 @@ struct ContentView: View {
                    let messages = viewModel.privateChats[peerID],
                    !messages.isEmpty {
                     withAnimation {
-                        proxy.scrollTo(messages.count - 1, anchor: .bottom)
+                        proxy.scrollTo(messages.last?.id, anchor: .bottom)
                     }
                 }
             }