Description

Added undo and redo functionality using keyboard shortcuts (Ctrl + Z, Ctrl + Y / Ctrl + Shift + Z). This includes maintaining undo and redo stacks, handling keyboard events, and updating the content and caret position accordingly.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Checklist:

• I'm sure that this PR is not a duplicate
• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes