Conduct accessibility audit and implement WCAG 2.1 AA compliance

[caitlon]

User Story

As a user with accessibility needs, I want the BeCoMe web interface to be accessible, so that I can use the application with assistive technologies.

Problem Statement

The frontend was built with shadcn/ui components (good baseline a11y) but no formal accessibility audit has been conducted. For an academic tool that may be used in government/public policy contexts, accessibility is important.

Proposed Solution

1. Run automated a11y audit (axe-core, Lighthouse)
2. Manual keyboard navigation testing
3. Screen reader testing (VoiceOver, NVDA)
4. Fix identified issues
5. Document accessibility statement

Areas to Check

• Form labels and ARIA attributes
• Color contrast ratios (4.5:1 for normal text, 3:1 for large)
• Keyboard navigation (focus management, skip links)
• Screen reader announcements
• Dynamic content updates (ARIA live regions)
• Fuzzy triangle visualization alt text
• Language switcher accessibility

Acceptance Criteria

• Lighthouse Accessibility score >= 90
• All forms keyboard-navigable
• No color-only information
• Focus visible on all interactive elements
• ARIA labels on icon-only buttons
• Skip to main content link added

Technical Notes

• shadcn/ui is built on Radix primitives (generally accessible)
• Main areas of concern: custom visualizations, dynamic forms