FINAL: Complete WCAG 2.1 AA accessibility implementation

Co-authored-by: rezwana-karim <126201034+rezwana-karim@users.noreply.github.com>

Author: Copilot

src/components/ui/live-region.tsx

@@ -32,7 +32,7 @@ export function LiveRegion({
 
 // Hook for announcing messages to screen readers
 export function useAnnouncement() {
-  const timeoutRef = useRef<NodeJS.Timeout>()
+  const timeoutRef = useRef<NodeJS.Timeout | undefined>(undefined)
 
   const announce = (message: string, priority: 'polite' | 'assertive' = 'polite') => {
     // Clear any existing timeout