feat: Sort selected workspace items by Z-index to ensure consistent order.

frontend/src/desktop/DesktopWorkspace.tsx

@@ -150,12 +150,21 @@ const DesktopWorkspaceContent: React.FC<DesktopWorkspaceProps> = ({
   } = useWorkspaceSelectionContext();
 
   const handleSelectionChange = useCallback((ids: Identifier[]) => {
+    // Sort IDs by Z-index (ascending) so the last item is the top-most
+    const sortedIds = [...ids].sort((a, b) => {
+      const cardA = layoutStore.items.get(String(a));
+      const cardB = layoutStore.items.get(String(b));
+      const zA = cardA ? cardA.z : -Infinity;
+      const zB = cardB ? cardB.z : -Infinity;
+      return zA - zB;
+    });
+
     if (setSelectedEntries) {
-      const keys = ids.map(id => createDocumentEntryKey(id));
+      const keys = sortedIds.map(id => createDocumentEntryKey(id));
       setSelectedEntries(keys);
     }
-    onSelectionChange?.(ids);
+    onSelectionChange?.(sortedIds);
-  }, [setSelectedEntries, onSelectionChange]);
+  }, [setSelectedEntries, onSelectionChange, layoutStore]);
 
   const onClearSelection = useCallback(() => {
     clearSelection ? clearSelection() : handleSelectionChange([]);