improve the CoverPage and make it more attractive and aesthetic (#372)

<!-- ISSUE & PR TITLE SHOULD BE SAME-->
## Description
changed the cover page with  aesthetic new background 
(this background is designed by me using canva)


## Related Issues

<!--Cite any related issue(s) this pull request addresses. If none,
simply state “None”-->
- Closes #294 

## Type of PR
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the below box -->
- [ ] ()

## Screenshots / videos (if applicable)
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changes-->

![Screenshot
(254)](https://github.com/user-attachments/assets/3895dcc9-5704-41e6-94b8-e39d7dcf0e95)

## Checklist
<!-- [X] - put a cross/X inside [] to check the box -->
- [ X] I have gone through the [contributing
guide](https://github.com/Anjaliavv51/Retro)
- [X ] I have updated my branch and synced it with project `main` branch
before making this PR
- [ X] I have performed a self-review of my code
- [ X] I have tested the changes thoroughly before submitting this pull
request.
- [ X] I have provided relevant issue numbers, screenshots, and videos
after making the changes.
- [ X] I have commented my code, particularly in hard-to-understand
areas.


## Additional context:
<!--Include any additional information or context that might be helpful
for reviewers.-->
I'd like to take any desirable inputs!
let me know you need any other changes