🎨 Palette: Semantic navigation and high-contrast focus indicators

[ISTEC-FOR340]

💡 What: The UX enhancement added

Refactored the navigation system on the landing page and subprojects.

• Converted non-semantic div cards and manual button back-links to semantic <a> tags.
• Implemented custom :focus-visible styles with a high-contrast double-ring effect.
• Optimized card CSS to use overflow: visible combined with pseudo-elements for backgrounds, ensuring that keyboard focus indicators are never clipped by the container boundaries.
• Removed script.js as native browser navigation now handles all routing.

🎯 Why: The user problem it solves

The previous implementation relied on JavaScript onclick handlers on non-interactive div elements. This prevented standard browser features like "Open in new tab", hindered SEO, and made keyboard navigation impossible without custom logic. Additionally, the dark glassmorphism theme lacked visible focus indicators, making the site difficult to navigate for keyboard-only users.

♿ Accessibility: Any a11y improvements made

• Semantic HTML: Replaced generic containers with appropriate interactive elements (<a>).
• Keyboard Navigation: Native tab order is now supported, and interactive elements have highly visible focus states.
• Invalid Nesting: Removed nested buttons inside card links to comply with ARIA and HTML standards.
• Visual Feedback: Focus rings are high-contrast and unclipped, providing clear feedback during navigation.

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PR created automatically by Jules for task 17937680064201418863 started by @ISTEC-FOR340

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