feat: Dashboard aria-live

[Derekwalter999]

Summary

This PR adds accessible aria-live status announcements to the Dashboard to improve screen reader support for dynamic UI updates, aligning with WCAG 2.1 AA accessibility requirements for the GrantFox FWC26 (Stellar Wave) campaign.

Changes Made

• Added a reusable LiveRegion component to announce dynamic status changes.
• Integrated aria-live announcements into the Dashboard for relevant state updates.
• Ensured announcements are non-intrusive and compatible with assistive technologies.
• Added focused unit/integration tests covering live region behavior and edge cases.
• Updated documentation to reflect the accessibility enhancement and any visible/API changes.

Files Changed

• src/pages/Dashboard.tsx
• src/components/LiveRegion.tsx
• Related test files
• Documentation (if applicable)

Testing

• ✅ Added focused tests for aria-live announcements.
• ✅ Verified Dashboard state changes are announced correctly by screen readers.
• ✅ Confirmed no regressions to existing Dashboard functionality.
• ✅ Ran project linting and test suite successfully.

Accessibility

• Meets WCAG 2.1 AA accessibility guidelines.
• Improves support for screen reader users through semantic live region announcements.
• Maintains responsive behavior, design-token usage, and dark-mode compatibility.

Checklist

• Implementation matches the issue requirements
• Tests added and passing
• Documentation updated
• Lint and formatting checks passed
• Secure and performant implementation
• Ready for code review

closes #557