♿️(frontend) update emoji hover background to meet RGAA contrast rules

Adjust background color of emoji hover state to ensure minimum visual
contrast ratio as recommended by accessibility consultant.
Change ensures compliance with RGAA accessibility standards.

src/frontend/src/features/rooms/livekit/components/controls/ReactionsToggle.tsx

@@ -129,7 +129,7 @@ export const ReactionsToggle = () => {
                   key={index}
                   onPress={() => sendReaction(emoji)}
                   aria-label={t('send', { emoji })}
-                  variant="quaternaryText"
+                  variant="primaryTextDark"
                   size="sm"
                   data-attr={`send-reaction-${emoji}`}
                 >