feat: 实现 Admin 首次初始化与网页登录 (#50)

admin/templates/partials/header.html

@@ -15,6 +15,13 @@
   <a href="/syb"     class="{{if eq .Active "syb"}}active{{end}}">顺运宝数据</a>
   <a href="/tasks"   class="{{if eq .Active "tasks"}}active{{end}}">采集采购</a>
   <a href="/clients" class="{{if eq .Active "clients"}}active{{end}}">客户端列表</a>
+  {{if .CurrentUser}}
+  <span class="nav-user">{{.CurrentUser.Username}}</span>
+  <form class="nav-logout" method="post" action="/logout">
+    <input type="hidden" name="csrf_token" value="{{.CSRFToken}}">
+    <button type="submit">退出登录</button>
+  </form>
+  {{end}}
 </nav>
 
 <main class="page">