Add HackSphere 2025 Landing Page with Countdown and Styling Fixes

[Amrutha621]

This pull request adds a new landing page for HackSphere 2025. The page includes:

• A styled navigation bar with links (Home, About, Schedule, Contact)
• A hero section with event name, tagline, date, and "Register Now" button
• A live countdown timer to the event date (June 20–22, 2025)
• An "About the Event" section
• Proper CSS styling with a gradient background
• Linked image (fixed file naming issue)

All files (index.html, style.css, image) are placed in the root directory for smooth deployment. This replaces the default README.md view on GitHub Pages and ensures the site displays correctly.

[abhips2005]

Try using any frameworks rather than HTML , css.