fix: forward InputMethodQuery to searchEdit for correct IME candidate window positioning

Override inputMethodQuery() virtual function in InputEventItem to forward input method queries to searchEdit. When IME queries cursor position for candidate window placement, the function forwards the query to searchEdit and maps the returned cursor rectangle coordinates from searchEdit's local coordinate system to InputEventItem's coordinate system. This ensures the candidate window appears at the correct position near the search box while keeping focus on InputEventItem.

Changes:
- Add inputMethodSource property to InputEventItem for specifying the text control to forward queries to
- Override inputMethodQuery() to forward queries and map coordinates for ImCursorRectangle
- Set inputMethodSource to searchEdit and add focus property in FullscreenFrame and WindowedFrame
- Remove redundant ImEnabled override as SearchEdit already returns correct state

重写 InputEventItem 的 inputMethodQuery() 虚函数，将输入法查询转发给 searchEdit。当输入法查询光标位置以定位候选框时，该函数将查询转发给 searchEdit，并将返回的光标矩形坐标从 searchEdit 的局部坐标系映射到 InputEventItem 的坐标系。这确保候选框出现在搜索框附近的正确位置，同时焦点保持在 InputEventItem 上。

修改内容：
- 为 InputEventItem 添加 inputMethodSource 属性，用于指定转发查询的文本控件
- 重写 inputMethodQuery() 以转发查询并映射 ImCursorRectangle 的坐标
- 在 FullscreenFrame 和 WindowedFrame 中设置 inputMethodSource 为 searchEdit 并添加 focus 属性
- 移除冗余的 ImEnabled 覆盖，因为 SearchEdit 已经返回正确状态

PMS: BUG-301743

Author: Ivy233

inputeventitem.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023 UnionTech Software Technology Co., Ltd.
+// SPDX-FileCopyrightText: 2023 - 2026 UnionTech Software Technology Co., Ltd.
 //
 // SPDX-License-Identifier: GPL-3.0-or-later
 #include "inputeventitem.h"
@@ -12,6 +12,33 @@ InputEventItem::InputEventItem()
     qApp->installEventFilter(this);
 }
 
+QQuickItem* InputEventItem::inputMethodSource() const
+{
+    return m_inputMethodSource;
+}
+
+void InputEventItem::setInputMethodSource(QQuickItem* source)
+{
+    if (m_inputMethodSource != source) {
+        m_inputMethodSource = source;
+        Q_EMIT inputMethodSourceChanged();
+    }
+}
+
+QVariant InputEventItem::inputMethodQuery(Qt::InputMethodQuery query) const
+{
+    if (m_inputMethodSource) {
+        if (query == Qt::ImCursorRectangle) {
+            QVariant result = m_inputMethodSource->inputMethodQuery(query);
+            QRectF rect = result.toRectF();
+            QPointF mapped = m_inputMethodSource->mapToItem(this, rect.topLeft());
+            rect.moveTopLeft(mapped);
+            return rect;
+        }
+    }
+    return QQuickItem::inputMethodQuery(query);
+}
+
 bool InputEventItem::eventFilter(QObject *obj, QEvent *event) {
     if (event->type() == QEvent::InputMethod && (this->children().contains(obj) || obj == this)) {
         QInputMethodEvent *inputMethodEvent = static_cast<QInputMethodEvent *>(event);

inputeventitem.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023 UnionTech Software Technology Co., Ltd.
+// SPDX-FileCopyrightText: 2023 - 2026 UnionTech Software Technology Co., Ltd.
 //
 // SPDX-License-Identifier: GPL-3.0-or-later
 #ifndef INPUTEVENTITEM_H
@@ -12,14 +12,24 @@ class InputEventItem : public QQuickItem
 {
     Q_OBJECT
     QML_ELEMENT
+    Q_PROPERTY(QQuickItem* inputMethodSource READ inputMethodSource WRITE setInputMethodSource NOTIFY inputMethodSourceChanged)
 public:
     InputEventItem();
 
+    QQuickItem* inputMethodSource() const;
+    void setInputMethodSource(QQuickItem* source);
+
+    QVariant inputMethodQuery(Qt::InputMethodQuery query) const override;
+
 protected:
     bool eventFilter(QObject *obj, QEvent *event) override;
 
 signals:
     void inputReceived(const QString &input);
+    void inputMethodSourceChanged();
+
+private:
+    QQuickItem* m_inputMethodSource = nullptr;
 };
 
 #endif // INPUTEVENTITEM_H

qml/FullscreenFrame.qml

@@ -18,6 +18,8 @@ import 'windowed' as WindowedLaunchpad
 InputEventItem {
     anchors.fill: parent
     objectName: "FullscreenFrame-InputEventItem"
+    inputMethodSource: searchEdit
+    focus: true
 
     property Palette appTextColor: Palette {
         normal {

qml/windowed/WindowedFrame.qml

@@ -16,6 +16,7 @@ import "."
 InputEventItem {
     id: baseLayer
     objectName: "WindowedFrame-BaseLayer"
+    inputMethodSource: bottomBar.searchEdit
 
     visible: true
     focus: true