fix(CopyButton): add aria-label for screen reader accessibility

Set aria-label to the same value as title so icon-only button is
properly announced by assistive technology.

src/components/CopyButton.tsx

@@ -53,6 +53,7 @@ export const CopyButton: React.FC<CopyButtonProps> = ({
       type="button"
       onClick={handleCopy}
       title={tooltip ?? t('buttons.copy')}
+      aria-label={tooltip ?? t('buttons.copy')}
       className={cn(
         buttonVariants({ variant, size }),
         copied &&