feat: Web端自动刷新画面机制

- DeviceScreen添加无帧超时检测(8秒无帧触发刷新)
- 自动发送REFRESH_SCREEN请求给服务端
- 15秒冷却期防止频繁刷新

src/components/Device/DeviceScreen.tsx

@@ -176,6 +176,49 @@ const DeviceScreen: React.FC<DeviceScreenProps> = ({ deviceId, onScreenSizeChang
     }
   }, [webSocket, deviceId])
 
+  // Auto-refresh: detect no-frame timeout and request screen refresh from device
+  const lastFrameTimeRef = useRef<number>(Date.now())
+  const refreshRequestedRef = useRef<boolean>(false)
+  const NO_FRAME_TIMEOUT = 8000 // 8 seconds without frames triggers refresh
+  const REFRESH_COOLDOWN = 15000 // minimum 15 seconds between refresh requests
+
+  // Update last frame time when screen_data arrives
+  useEffect(() => {
+    if (!webSocket || !deviceId) return
+
+    const trackFrameTime = (data: any) => {
+      if (data.deviceId === deviceId) {
+        lastFrameTimeRef.current = Date.now()
+        refreshRequestedRef.current = false
+      }
+    }
+
+    webSocket.on('screen_data', trackFrameTime)
+    return () => { webSocket.off('screen_data', trackFrameTime) }
+  }, [webSocket, deviceId])
+
+  // Periodic check for frame timeout
+  useEffect(() => {
+    if (!webSocket || !deviceId) return
+
+    const checkInterval = window.setInterval(() => {
+      const elapsed = Date.now() - lastFrameTimeRef.current
+      if (elapsed < NO_FRAME_TIMEOUT) return
+      if (refreshRequestedRef.current) return
+
+      console.log(`[AutoRefresh] No frames for ${Math.round(elapsed / 1000)}s, requesting screen refresh`)
+      refreshRequestedRef.current = true
+      lastFrameTimeRef.current = Date.now() - NO_FRAME_TIMEOUT + REFRESH_COOLDOWN
+
+      webSocket.emit('client_event', {
+        type: 'REFRESH_SCREEN',
+        data: { deviceId }
+      })
+    }, 3000) // check every 3 seconds
+
+    return () => { clearInterval(checkInterval) }
+  }, [webSocket, deviceId])
+
   // 控制权管理的独立useEffect，只在必要时申请/释放
   useEffect(() => {
     if (!webSocket || !deviceId) return