feat: add admin panel button for staff users

lmsege/lms/templates/lms/base.html

@@ -24,6 +24,9 @@
                 </div>
                 <div class="flex items-center gap-4">
                     {% if user.is_authenticated %}
+                        {% if user.is_staff %}
+                            <a href="{% url 'admin:index' %}" class="text-sm font-medium text-purple-600 hover:text-purple-800 transition">Админ-панель</a>
+                        {% endif %}
                         <span class="text-sm text-gray-600">Привет, <b>{{ user.first_name|default:user.username }}</b></span>
                         <form action="{% url 'lms:logout' %}" method="post" class="inline">
                             {% csrf_token %}