Fix: Prevent heap-use-after-free crash when importing XML via Script Editor (#8470)

This fixes a regression where importing an XML file via the Import button
in the Script Editor caused a heap-use-after-free crash, while drag-and-drop
of the same file worked fine.

Root cause:
In slot_import(), after clearing all tree widgets, the current item pointers
(mpCurrentTriggerItem, mpCurrentTimerItem, etc.) were left pointing to freed
memory. When slot_profileSaveAction() was subsequently called, it invoked
slot_saveEdits(), which attempted to save using these dangling pointers,
resulting in a crash when accessing freed QTreeWidgetItem objects.

Solution:
Clear all current item pointers immediately after clearing tree widgets and
BEFORE calling slot_profileSaveAction(). This ensures that the save
operations in slot_saveEdits() will safely early-return due to nullptr checks
at the beginning of each save function (saveTrigger(), saveTimer(), etc.).

This follows the same pattern used in runScheduledCleanReset() which has a
similar comment explaining the same safety measure.

The import still succeeds (the script is imported), but now without crashing.

Author: claude

src/dlgTriggerEditor.cpp

@@ -11500,17 +11500,18 @@ void dlgTriggerEditor::slot_import()
     treeWidget_keys->clear();
     treeWidget_scripts->clear();
 
-    slot_profileSaveAction();
-
-    fillout_form();
-
+    // Nullify current item pointers before saving to prevent use-after-free
     mpCurrentTriggerItem = nullptr;
     mpCurrentTimerItem = nullptr;
     mpCurrentAliasItem = nullptr;
     mpCurrentScriptItem = nullptr;
     mpCurrentActionItem = nullptr;
     mpCurrentKeyItem = nullptr;
 
+    slot_profileSaveAction();
+
+    fillout_form();
+
     slot_showTriggers();
 }