fix(admin): 浏览器直接访问后台时渲染登录页而非401 JSON

- AdminAuth 中间件：GET 页面请求未登录时返回 login 页，API 请求仍返回 401
- 新增 Login.js 登录页组件（密码输入 + 登录后跳回原页面）
- index.html 注册 login 页面路由

server/internal/middleware/middleware.go

@@ -104,6 +104,7 @@ func Auth() gin.HandlerFunc {
 }
 
 // AdminAuth 管理员认证中间件：要求携带 role=admin 的 JWT（Authorization 头或 HttpOnly Cookie）
+// 浏览器导航（GET 页面请求）未登录时渲染登录页；API 请求未登录时返回 401 JSON
 func AdminAuth() gin.HandlerFunc {
 	return func(c *gin.Context) {
 		tokenString := ""
@@ -115,18 +116,24 @@ func AdminAuth() gin.HandlerFunc {
 			tokenString, _ = c.Cookie(service.AdminTokenCookie)
 		}
 
-		if tokenString == "" {
-			c.JSON(http.StatusUnauthorized, gin.H{
-				"code": 401,
-				"msg":  "需要管理员权限",
-			})
-			c.Abort()
-			return
+		authed := false
+		if tokenString != "" {
+			cfg := config.Load()
+			userService := service.NewUserService()
+			authed = userService.IsAdminToken(tokenString, cfg.JWT.Secret)
 		}
 
-		cfg := config.Load()
-		userService := service.NewUserService()
-		if !userService.IsAdminToken(tokenString, cfg.JWT.Secret) {
+		if !authed {
+			// 页面导航（GET 且非 /admin/api/）：返回登录页
+			if c.Request.Method == http.MethodGet && !strings.HasPrefix(c.Request.URL.Path, "/admin/api/") {
+				c.HTML(http.StatusOK, "index.html", gin.H{
+					"title": "管理员登录",
+					"page":  "login",
+					"url":   c.Request.URL.Path,
+				})
+				c.Abort()
+				return
+			}
 			c.JSON(http.StatusUnauthorized, gin.H{
 				"code": 401,
 				"msg":  "需要管理员权限",

server/web/index.html

@@ -19,6 +19,7 @@
         createInertiaApp({
             resolve: name => {
                 const pages = {
+                    login: () => import('/static/js/pages/Login.js'),
                     dashboard: () => import('/static/js/pages/Dashboard.js'),
                     users: () => import('/static/js/pages/Users.js'),
                     orders: () => import('/static/js/pages/Orders.js'),

server/web/static/js/pages/Login.js

@@ -0,0 +1,68 @@
+// Login 管理员登录页
+export default {
+    template: `
+        <div class="min-h-screen bg-gray-100 flex items-center justify-center px-4">
+            <div class="max-w-sm w-full bg-white rounded-lg shadow-md p-8">
+                <div class="text-center mb-6">
+                    <h1 class="text-2xl font-bold text-red-600">祈福小助手</h1>
+                    <p class="text-gray-500 text-sm mt-1">管理后台登录</p>
+                </div>
+                <form @submit.prevent="submit">
+                    <div class="mb-4">
+                        <label class="block text-sm font-medium text-gray-700 mb-1">管理密码</label>
+                        <input
+                            v-model="password"
+                            type="password"
+                            autocomplete="current-password"
+                            placeholder="请输入 ADMIN_PASSWORD"
+                            class="w-full px-3 py-2 border border-gray-300 rounded-md focus:outline-none focus:ring-2 focus:ring-red-500 focus:border-transparent"
+                            :disabled="loading"
+                        />
+                    </div>
+                    <div v-if="error" class="mb-4 text-sm text-red-600">{{ error }}</div>
+                    <button
+                        type="submit"
+                        :disabled="loading || !password"
+                        class="w-full bg-red-600 text-white py-2 rounded-md hover:bg-red-700 disabled:opacity-50 disabled:cursor-not-allowed transition"
+                    >
+                        {{ loading ? '登录中...' : '登 录' }}
+                    </button>
+                </form>
+            </div>
+        </div>
+    `,
+    data() {
+        return {
+            password: '',
+            loading: false,
+            error: ''
+        };
+    },
+    methods: {
+        async submit() {
+            if (!this.password || this.loading) return;
+            this.loading = true;
+            this.error = '';
+            try {
+                const res = await fetch('/admin/login', {
+                    method: 'POST',
+                    headers: { 'Content-Type': 'application/json' },
+                    body: JSON.stringify({ password: this.password })
+                });
+                const data = await res.json();
+                if (data.code === 0) {
+                    // Cookie 已由服务端写入，跳回原本要访问的页面
+                    window.location.href = window.location.pathname === '/admin/login'
+                        ? '/admin/'
+                        : window.location.pathname;
+                } else {
+                    this.error = data.msg || '登录失败';
+                }
+            } catch (e) {
+                this.error = '网络错误，请重试';
+            } finally {
+                this.loading = false;
+            }
+        }
+    }
+};