feat: enhance accessibility and focus styles

[barbaraperic]

Description

• Added global focus styles to improve keyboard navigation and accessibility.
• Updated Carousel component not to be focusable by adding tabindex="-1" (not an interactive element)
• Enhanced EcosystemCard and Header components with tabindex attributes for better accessibility.
• Refactored Blog Card component to improve structure and maintainability by moving the image outside of the AppLink.

These changes aim to create a more inclusive user experience and ensure compliance with accessibility standards.

Video

CleanShot.2025-05-28.at.10.34.12.mp4