fix(ComboBox): fix highlight lingering after mouse leaves

- Track the popup's hover state by adding a isInteractingWithContent property,
and modify the highlighted property in the delegate.
- The logic of the highlighted property now depends on
isInteractingWithContent, automatically clearing the highlight when the
mouse leaves.

修复鼠标移出后高亮项仍然残留的问题

- 通过添加isInteractingWithContent属性跟踪popup悬停状态，修改delegate的highlighted
- highlighted 属性逻辑依赖isInteractingWithContent，鼠标离开时自动清除高亮

Log: 修复ComboBox的菜单项鼠标离开后高亮残留问题
Influence: ComboBox菜单项
PMS: BUG-304991

Author: electricface

qt6/src/qml/ComboBox.qml

@@ -36,7 +36,7 @@ T.ComboBox {
         useIndicatorPadding: true
         text: control.textRole ? (Array.isArray(control.model) ? modelData[control.textRole] : (model[control.textRole] === undefined ? modelData[control.textRole] : model[control.textRole])) : modelData
         icon.name: (control.iconNameRole && model[control.iconNameRole] !== undefined) ? model[control.iconNameRole] : null
-        highlighted: control.highlightedIndex === index
+        highlighted: popup.isInteractingWithContent ? control.highlightedIndex === index : false
         hoverEnabled: control.hoverEnabled
         autoExclusive: true
         checked: control.currentIndex === index
@@ -169,6 +169,18 @@ T.ComboBox {
         rightMargin: DS.Style.popup.margin
         palette: control.palette
         implicitWidth: control.flat ? Math.max(contentItem.implicitWidth, control.width) : control.width
+        property bool isInteractingWithContent: false
+        onClosed: isInteractingWithContent = false
+        Connections {
+            target: control
+            function onHighlightedIndexChanged() {
+                if (control.highlightedIndex >= 0)
+                    popup.isInteractingWithContent = true
+            }
+        }
+        HoverHandler {
+            onHoveredChanged: popup.isInteractingWithContent = hovered
+        }
         contentItem: ArrowListView {
             clip: true
             maxVisibleItems: control.maxVisibleItems