Admin group: single table, defense actions in cells; flash messages as toasts

web/src/main/resources/templates/admin/groups.html

@@ -4,8 +4,6 @@
 <body>
 <div id="content">
     <h1 class="page-title">Группы</h1>
-    <div th:if="${notice}" class="alert alert-success" th:text="${notice}"></div>
-    <div th:if="${error}" class="alert alert-error" th:text="${error}"></div>
     <div class="grid grid-2">
         <form class="card form-card form-stack" th:action="@{/admin/groups}" method="post">
             <h2 class="section-title">Создать группу</h2>