Title: UI improvements in TO-DO List and addition of button to mark TODO as completed

[AtharvKasar04]

Is your feature request related to a problem? Please describe.

• The buttons to edit and remove 'TODO' aren't centered horizontally inside the TODO's element.
• Additionally, a separate checkbox or a button can be added to mark the TODO/task as completed.

Describe the solution you'd like.

Addition of a button and fixing the UI changes.

Describe alternatives you've considered.

UI improvements to make it look more appealing to the users.

Add any other context or screenshots about the feature request here.

@swapnilsparsh Can you please assign this issue to me under GSSoC'24 to work on this. It would be great for me to work on this.