Implement accessibility improvements

[Dustin-Reyes]

Ensure menu is fully accessible.

Tasks:

• Proper heading hierarchy (h1, h2, h3)
• Keyboard navigation for category nav
• ARIA labels for search and interactive elements
• Focus management
• Alt text for all images
• Test with screen reader
• Ensure color contrast meets WCAG AA

Acceptance Criteria:

• Keyboard navigation works throughout
• Screen reader can navigate menu
• All interactive elements are labeled
• Color contrast passes WCAG AA

Milestone: Polish (Phase 5)