Add visual feedback for unread messages in the menu. Implement a pulsing animation and color change for the inbox button when there are unread chats. Also, add sound notification for new messages received, enhancing user experience.

client/src/components/MenuBar.vue

@@ -7,7 +7,7 @@
       </span>
       <button @click="handleLeave">{{ $t('menu_leave') }}</button>
       <button @click="handleSearch">{{ $t('menu_search') }}</button>
-      <button @click="handleInbox">
+      <button @click="handleInbox" :class="{ 'has-unread': chatStore.unreadChatsCount > 0 }">
         {{ $t('menu_inbox') }}<span v-if="chatStore.unreadChatsCount > 0"> ({{ chatStore.unreadChatsCount }})</span>
       </button>
       <button @click="handleHistory">{{ $t('menu_history') }}</button>