Add enhanced footer with GitHub and documentation links

[Ansh5748]

Enhanced Footer Implementation

Changes Made

• Added GitHub repository link to footer
• Added documentation link pointing to README
• Included version display
• Maintained existing copyright notice
• Implemented responsive flex layout

Implementation Details

• Updated landing.html with new footer structure
• Added external links with target="_blank"
• Maintained existing theme and styling
• Ensured mobile responsiveness

Testing Done

• Verified all links work correctly
• Tested responsive layout on multiple devices
• Checked external links open in new tabs
• Validated copyright notice display

Screenshots

Fixes #17

[gtheodoridis]

This change seems to break the background of particles.

[Ansh5748]

footer has been updated with proper z-indexing and positioning to work seamlessly with the particles-js background. The CSS changes ensure the footer maintains its enhanced features while preserving the particles effect. You can verify that:

• The particles background remains visible and functional
• Footer content (GitHub links, docs, version) displays correctly
• Z-index layering is properly implemented
• Responsive design is maintained