Fix private message notifications and chat updates

- Remove self-notification when sending private messages
- Clear unread indicator when viewing active chat
- Properly update UI when private messages are sent/received
- Prevent duplicate messages in chat history
- Use objectWillChange to force SwiftUI updates

bitchat/Services/BluetoothMeshService.swift

@@ -226,10 +226,7 @@ class BluetoothMeshService: NSObject {
                 print("[DEBUG] Sending private message to \(recipientNickname): \(content)")
                 self.broadcastPacket(packet)
                 
-                // Also show the message locally
-                DispatchQueue.main.async {
-                    self.delegate?.didReceiveMessage(message)
-                }
+                // Don't call didReceiveMessage here - let the view model handle it directly
             }
         }
     }