Fix: prevent mobile web remote desktop freeze on Safari app-switch

by forcing clean WS reconnect on foreground return;

add 30-second grace period on server to avoid cold-start on quick reconnects

server/2015Remote/WebService.h

@@ -5,6 +5,8 @@
 #include <vector>
 #include <map>
 #include <set>
+#include <atomic>
+#include <chrono>
 #include <mutex>
 #include <thread>
 #include <memory>
@@ -231,6 +233,13 @@ private:
     std::set<uint64_t> m_OfflineDevices;  // Devices that went offline since last flush
     std::mutex m_DirtyDevicesMutex;
 
+    // Grace-period timers: delay CloseWebRemoteDesktopByClientID by 30 s after
+    // the last web viewer disconnects to allow quick mobile reconnects (e.g.
+    // switching to a TOTP app briefly). Cancelled by StartRemoteDesktop when a
+    // viewer reconnects within the window.
+    std::map<uint64_t, std::shared_ptr<std::atomic<bool>>> m_PendingCloseTimers;
+    std::mutex m_PendingCloseMutex;
+
 public:
     // Check if a device session was triggered by web (should be hidden)
     bool IsWebTriggered(uint64_t device_id);