[ENHANCEMENT] Implement keyboard navigation and focus management

Describe the current behavior

The application lacks comprehensive keyboard navigation and proper focus management. While basic tab navigation works, there's no proper focus handling for modals, complex components, or dynamic content updates.

Describe the desired improvement

• Implement logical tab order for all interactive elements
• Add keyboard shortcuts for common actions
• Create focus trap for modal dialogs
• Implement proper focus management for dynamic content
• Add visible focus indicators that meet WCAG contrast requirements
• Ensure all interactive elements are keyboard-accessible
• Add skip links for main content areas
• Implement proper focus restoration after modal closing

Why is this improvement important?

Proper keyboard navigation and focus management are crucial for users who rely on keyboards and assistive technologies. It improves accessibility and provides a better experience for power users.

Alternatives Considered

• Voice navigation (too complex)
• Mouse keys support (OS-level feature)
• Custom focus management library (unnecessary complexity)

Additional context

Focus on:

• Modal components (especially ResumeLoader.vue)
• Form components (particularly TechSelectMenu.vue)
• Dynamic content areas
• Navigation elements