fix: set focus to search edit when launcher becomes visible

When the launcher is shown, the keyboard focus remains on the root
InputEventItem instead of the search edit. This causes two issues:
1. The cursor does not appear in the search bar on each open.
2. The IME candidate window is not visible during the preedit phase
   (e.g. typing pinyin), because InputEventItem is not a text input
   widget and cannot provide cursor geometry for IME positioning.

Fix by calling forceActiveFocus() on the search edit when the launcher
becomes visible, for both windowed and fullscreen modes.

修复启动器显示时搜索框未获得焦点的问题。启动器打开时键盘焦点停留在根节点
InputEventItem 上而非搜索框，导致光标不在搜索栏，且中文输入法预编辑阶段
（如拼音输入时）候选框不可见。在启动器可见时对搜索框调用 forceActiveFocus()
以修复此问题，同时修复窗口模式和全屏模式。

PMS: BUG-301743

Author: Ivy233

qml/FullscreenFrame.qml

@@ -883,8 +883,12 @@ InputEventItem {
         Connections {
             target: LauncherController
             function onVisibleChanged() {
+                if (LauncherController.visible) {
+                    searchEdit.forceActiveFocus()
+                    return
+                }
+
                 // only do these clean-up steps on launcher get hide
-                if (LauncherController.visible) return
                 // clear searchEdit text
                 searchEdit.text = ""
                 if (listviewPage.currentItem) {

qml/windowed/WindowedFrame.qml

@@ -303,9 +303,12 @@ InputEventItem {
     Connections {
         target: LauncherController
         function onVisibleChanged() {
-            // only do these clean-up steps on launcher get hide
-            if (LauncherController.visible) return
+            if (LauncherController.visible) {
+                bottomBar.searchEdit.forceActiveFocus()
+                return
+            }
 
+            // only do these clean-up steps on launcher get hide
             // clear searchEdit text
             bottomBar.searchEdit.text = ""
             // reset(remove) keyboard focus