Add bundled ListBox Gallery example project

Add a bundled Objo Studio example project that demonstrates the desktop ListBox control in a practical, user-editable table. The example should show normal text columns, checkbox columns, editable text cells, header sorting, column widths, grid lines, multi-selection, and key ListBox events such as CellEdited, CellPressed, CellDoublePressed, and HeaderPressed.

This gives users a runnable reference for common ListBox workflows directly from the Solution Chooser examples list.