[feat] add Windows privacy screen and prefer DXGI capture

apps/desktop/src/gui/runtime/peer_event_handler.cpp

@@ -405,6 +405,20 @@ void PeerEventHandler::OnConnectionStatus(ConnectionStatus status,
     runtime->show_connection_status_window_ = true;
     {
       std::unique_lock lock(runtime->connection_status_mutex_);
+#ifdef _WIN32
+      if (status == ConnectionStatus::Connected &&
+          runtime->config_center_->IsEnablePrivacyScreen() &&
+          std::none_of(runtime->connection_status_.begin(),
+                       runtime->connection_status_.end(), [](const auto& entry) {
+                         return entry.second == ConnectionStatus::Connected;
+                       })) {
+        // Pause before Connected becomes observable by capture/input threads.
+        // Only the first controller takes over local input. A later join must
+        // not release an existing controller's keys or re-enable privacy that
+        // the current session explicitly turned off.
+        runtime->privacy_.EnableOnConnection();
+      }
+#endif
       runtime->connection_status_[remote_id] = status;
     }