Add Widget Text

Recommended sequence:

1. widget_tree_inspect to find the current WidgetTree.
2. widget_palette to find TextBlock or another widget class.
3. schema_inspect for widget_tree_edit operation addFromPalette.
4. widget_tree_edit to add the widget under the chosen parent.
5. widget_inspect for the widget instance before setting properties.
6. widget_tree_edit to set widget or slot properties.
7. widget_compile.

Use WidgetTree tools for hierarchy changes. Use inspect results to choose property names and slot property paths.