fix: reset page index on frame change

Added onCurrentFrameChanged handler to reset listviewPage index to 0
when switching to FullscreenFrame
Previously the page reset only occurred on escape key press, but now it
also triggers when navigating back to FullscreenFrame
This ensures consistent behavior when returning to the fullscreen view
from other frames

fix: 在框架切换时重置页面索引

添加 onCurrentFrameChanged 处理程序，在切换到 FullscreenFrame 时将
listviewPage 索引重置为 0
之前页面重置仅在按下 escape 键时发生，现在在导航回 FullscreenFrame 时也
会触发
这确保了从其他框架返回全屏视图时行为的一致性

Pms: BUG-288417

Author: wjyrich

qml/FullscreenFrame.qml

@@ -734,8 +734,11 @@ InputEventItem {
                 if (folderGridViewPopup.visible) folderGridViewPopup.close()
                 // reset(remove) keyboard focus
                 baseLayer.focus = true
-                // reset page to the first page
-                listviewPage.setCurrentIndex(0)
+            }
+            function onCurrentFrameChanged() {
+                if (LauncherController.currentFrame === "FullscreenFrame") {
+                    listviewPage.setCurrentIndex(0)
+                }
             }
         }
     }