fix: implement tab arrow navigation and dynamic focus management

[simbongile-mkhotheli]

Summary

Improve keyboard accessibility and focus management across interactive components by implementing accessible tab navigation, dynamic focus handling, and better screen reader feedback.

Type of Change

• Bug fix
• Feature
• Refactor
• Documentation
• Test
• Chore

Changes

• Add arrow key navigation and tabIndex management to all tab components
• Implement focus management during mock interview question transitions
• Add aria-live regions for background processing and status updates
• Standardize role="alert" for error messages
• Improve loading indicators for assistive technologies

Testing

• npm run lint
• npm test
• npm run build
• Manual browser testing
• Verified keyboard navigation for all tab interfaces
• Verified focus moves appropriately during question transitions
• Verified status and error announcements with screen readers

Notes

This PR strengthens accessibility by improving keyboard interaction patterns, focus management, and assistive technology support. The changes align with WCAG 2.1,2 AA recommendations while maintaining existing functionality and user experience.