fix: 窗口居中加Screen.virtualX/virtualY偏移适配多显示器

原 Screen.width/height 居中在虚拟桌面原点，多显示器下窗口可能出
现在非预期屏幕。加 virtualX/virtualY 偏移后在任务栏所在屏幕内居中。

package/components/AboutWindow.qml

@@ -48,8 +48,10 @@ Window {
 
     onVisibleChanged: {
         if (visible) {
-            x = (Screen.width - width) / 2
-            y = (Screen.height - height) / 2
+            // 居中到当前屏幕（任务栏所在屏幕），加 virtualX/virtualY 偏移
+            // 避免多显示器下窗口出现在非预期屏幕
+            x = Screen.virtualX + (Screen.width - width) / 2
+            y = Screen.virtualY + (Screen.height - height) / 2
         }
     }
 

package/components/SettingsWindow.qml

@@ -97,11 +97,12 @@ Window {
         return "◉"                                  // 其他：通用网络节点
     }
 
-    // 显示时居中到桌面
+    // 显示时居中到当前屏幕（任务栏所在屏幕）
     onVisibleChanged: {
         if (visible) {
-            x = (Screen.width - width) / 2
-            y = (Screen.height - height) / 2
+            // 加 virtualX/virtualY 偏移，避免多显示器下窗口出现在非预期屏幕
+            x = Screen.virtualX + (Screen.width - width) / 2
+            y = Screen.virtualY + (Screen.height - height) / 2
         }
     }
 

package/components/TrafficChartWindow.qml

@@ -95,8 +95,10 @@ Window {
 
     onVisibleChanged: {
         if (visible) {
-            x = (Screen.width - width) / 2
-            y = (Screen.height - height) / 2
+            // 居中到当前屏幕（任务栏所在屏幕），加 virtualX/virtualY 偏移
+            // 避免多显示器下窗口出现在非预期屏幕
+            x = Screen.virtualX + (Screen.width - width) / 2
+            y = Screen.virtualY + (Screen.height - height) / 2
         }
     }