Feature: Exclude human Web viewing from MCP remote control sessions

Complete the bidirectional mutual exclusion between MCP remote control
and human Web viewing (§8.2). Direction 1 (remote_open rejected while a
human session holds the screen sub-connection) already existed; this adds
direction 2: a human Web viewer is now rejected while an MCP session owns
the device.

Add a m_McpTriggeredDevices marker (mirroring m_MfcTriggeredDevices) that
is set when an MCP session is created (BeginScreenCtrlOpen) and cleared at
every session-erasure site (CloseScreenCtrlSession, SweepIdleScreenCtrl,
OnScreenControlClosed, EndScreenCtrlAction), so the marker cannot go stale
and permanently block humans. HandleConnect checks IsMcpTriggered before
mutating client state or starting the remote desktop.

Co-Authored-By: deepseek-v4-pro

server/2015Remote/WebService.h

@@ -299,6 +299,12 @@ public:
     bool IsMfcTriggered(uint64_t device_id);
     void ClearMfcTriggered(uint64_t device_id);
 
+    // MCP trigger management - an MCP remote control session owns the screen
+    // sub-connection and blocks human Web viewing (bidirectional mutex, §8.2).
+    void SetMcpTriggered(uint64_t device_id);
+    bool IsMcpTriggered(uint64_t device_id);
+    void ClearMcpTriggered(uint64_t device_id);
+
     // Check if a remote desktop session already exists for device
     bool HasActiveSession(uint64_t device_id);
 
@@ -344,6 +350,10 @@ private:
     std::set<uint64_t> m_MfcTriggeredDevices;
     std::mutex m_MfcTriggeredMutex;
 
+    // MCP triggered devices: screen sub-connection owned by an MCP remote control session
+    std::set<uint64_t> m_McpTriggeredDevices;
+    std::mutex m_McpTriggeredMutex;
+
     // Web 终端会话状态
     struct WebTermSession {
         void* ws_ptr;                  // browser WebSocket