/claim #707 /closes #707

DESCRIPTION:

Implement a comprehensive undo/redo system for the Mudlet Script Editor using QUndoStack and QUndoCommand.

This change introduces undo/redo functionality for all major actions within the script editor, including:

Adding and deleting Triggers, Aliases, Timers, Scripts, and Keys.

Modifying all properties of these items.

Toggling the active state of items.

The implementation follows the Command pattern, with specific QUndoCommand subclasses for each action. This ensures that all operations are reversible.

The UI is updated with undo/redo buttons in the toolbar, and the corresponding actions are also added to the context menu.