feat: 全站登录保护，管理后台仅管理员可访问

- tasks 路由级认证保护，所有 API 需登录
- 未登录时显示登录页面，不暴露导航和功能
- ConfigView 仅管理员可访问，普通用户显示权限提示
- BuildView/HistoryView 所有 API 请求携带 token

frontend/src/App.vue

@@ -3,35 +3,46 @@
     <header class="header">
       <h1>iOS 自动打包服务</h1>
       <div class="header-right">
-        <nav class="nav">
+        <nav v-if="isLoggedIn" class="nav">
           <router-link to="/build">打包</router-link>
           <router-link to="/history">历史</router-link>
-          <router-link v-if="isLoggedIn" to="/admin">管理</router-link>
+          <router-link v-if="isAdmin" to="/admin">管理</router-link>
         </nav>
         <div v-if="!isLoggedIn" class="user-info">
           <button class="btn-login" @click="showLogin = true">登录</button>
         </div>
         <div v-else class="user-info">
-          <div class="user-avatar">A</div>
-          <span class="user-name">管理员</span>
+          <div class="user-avatar">{{ isAdmin ? 'A' : 'U' }}</div>
+          <span class="user-name">{{ isAdmin ? '管理员' : '用户' }}</span>
           <button class="btn-logout" @click="logout">退出</button>
         </div>
       </div>
     </header>
 
-    <router-view />
+    <template v-if="isLoggedIn">
+      <router-view />
+    </template>
+    <template v-else>
+      <div class="login-required">
+        <div class="login-card">
+          <h2>请先登录</h2>
+          <p>使用此服务需要登录账号</p>
+          <button class="login-btn" @click="showLogin = true">立即登录</button>
+        </div>
+      </div>
+    </template>
 
     <!-- 登录弹窗 -->
     <div v-if="showLogin" class="modal-overlay" @click.self="showLogin = false">
       <div class="login-modal">
-        <h2>管理员登录</h2>
+        <h2>用户登录</h2>
         <div class="form-group">
           <label>用户名</label>
-          <input v-model="loginForm.username" type="text" placeholder="请输入用户名">
+          <input v-model="loginForm.username" type="text" placeholder="请输入用户名" @keyup.enter="login">
         </div>
         <div class="form-group">
           <label>密码</label>
-          <input v-model="loginForm.password" type="password" placeholder="请输入密码">
+          <input v-model="loginForm.password" type="password" placeholder="请输入密码" @keyup.enter="login">
         </div>
         <button class="login-btn" @click="login">登录</button>
         <div class="login-hint">默认账号: admin / admin123</div>
@@ -44,12 +55,14 @@
 import { ref, onMounted, provide } from 'vue'
 
 const isLoggedIn = ref(false)
+const isAdmin = ref(false)
 const showLogin = ref(false)
 const loginForm = ref({ username: '', password: '' })
 
 // 提供给子组件使用
 provide('showLogin', showLogin)
 provide('isLoggedIn', isLoggedIn)
+provide('isAdmin', isAdmin)
 
 // 获取存储的 token
 const getToken = () => localStorage.getItem('authToken') || ''
@@ -67,9 +80,9 @@ const login = async () => {
     if (res.ok) {
       const data = await res.json()
       isLoggedIn.value = true
+      isAdmin.value = data.is_admin
       showLogin.value = false
       localStorage.setItem('authToken', data.token)
-      localStorage.setItem('isAdmin', 'true')
     } else {
       alert('用户名或密码错误')
     }
@@ -80,27 +93,31 @@ const login = async () => {
 
 const logout = () => {
   isLoggedIn.value = false
+  isAdmin.value = false
   localStorage.removeItem('authToken')
-  localStorage.removeItem('isAdmin')
 }
 
 // 检查登录状态（验证 token 有效性）
 onMounted(async () => {
   const token = localStorage.getItem('authToken')
-  if (!token) return
+  if (!token) {
+    showLogin.value = true
+    return
+  }
   try {
     const res = await fetch('/api/auth/me', {
       headers: { 'Authorization': `Bearer ${token}` },
     })
     if (res.ok) {
+      const data = await res.json()
       isLoggedIn.value = true
+      isAdmin.value = data.is_admin
     } else {
-      // token 无效或过期，清除
       localStorage.removeItem('authToken')
-      localStorage.removeItem('isAdmin')
+      showLogin.value = true
     }
   } catch {
-    // 网络错误时不清除，保持登录状态
+    // 网络错误时保持当前状态
   }
 })
 </script>
@@ -116,12 +133,17 @@ body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; b
 .nav a.router-link-active { background: #16213e; color: white; }
 .nav a:hover { color: white; }
 .user-info { display: flex; align-items: center; gap: 10px; }
-.user-avatar { width: 32px; height: 32px; background: #1890ff; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 14px; }
+.user-avatar { width: 32px; height: 32px; background: #1890ff; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 14px; font-weight: 600; }
 .user-name { font-size: 14px; }
 .btn-login { background: #1890ff; color: white; border: none; padding: 6px 16px; border-radius: 4px; cursor: pointer; font-size: 13px; }
 .btn-logout { background: transparent; color: #a0a0a0; border: 1px solid #444; padding: 6px 16px; border-radius: 4px; cursor: pointer; font-size: 13px; }
 .btn-logout:hover { border-color: #ff4d4f; color: #ff4d4f; }
 
+.login-required { display: flex; align-items: center; justify-content: center; min-height: calc(100vh - 64px); }
+.login-card { background: white; border-radius: 12px; padding: 48px; text-align: center; box-shadow: 0 2px 12px rgba(0,0,0,0.08); }
+.login-card h2 { font-size: 20px; color: #1a1a2e; margin-bottom: 8px; }
+.login-card p { color: #999; margin-bottom: 24px; }
+
 .modal-overlay { position: fixed; top: 0; left: 0; right: 0; bottom: 0; background: rgba(0,0,0,0.5); display: flex; align-items: center; justify-content: center; z-index: 1000; }
 .login-modal { background: white; border-radius: 12px; padding: 32px; width: 400px; }
 .login-modal h2 { font-size: 20px; margin-bottom: 24px; text-align: center; color: #1a1a2e; }