Polish logout page and management document styling

src/ElectionSystem.Api/Pages/Account/Logout.cshtml

@@ -1,3 +1,3 @@
 @page "/account/logout"
 @model ElectionSystem.Api.Pages.Account.LogoutModel
-<form method="post" id="logout-form"><button type="submit">退出登录</button></form>
+<section class="logout-page"><p>正在准备退出登录。</p><form method="post" id="logout-form"><button class="admin-button" type="submit">确认退出</button></form></section>

src/ElectionSystem.Api/Pages/Account/_ViewStart.cshtml

@@ -0,0 +1,3 @@
+@{
+    Layout = "_ManagementLayout";
+}

src/ElectionSystem.Api/Pages/Admin/_ViewStart.cshtml

@@ -0,0 +1,3 @@
+@{
+    Layout = "_ManagementLayout";
+}