feat: Enhance admin login and registration page

[alienx5499]

• Added loading indicators for login and signup buttons.
• Improved error handling and user feedback during form submission.
• Implemented password visibility toggle for improved usability.
• Refined structure and functionality for better user experience.

Dear @tushargupta1504,
Looking forward to your feedback and hoping this makes the user experience even better! 😊
Everything should now look great on all devices. Feel free to review and share your thoughts! 🌟
Also, could you please add the hacktoberfest-accepted and the gssoc-ext label to this PR and merge it when you get a chance? It would be greatly appreciated! 🙏

[github-actions]

🎉 Thank you for your contribution! Your pull request has been submitted successfully. A maintainer will review it as soon as possible. We appreciate your support in making this project better

[tushargupta1504]