fix: 退出登录后在受保护页面跳转到配方查询页面

在 router/index.js 中为需要登录才能访问的路由（manage、inventory、
projects、mydiary、audit、bugs、users）添加 meta.requiresAuth 标记。

在 UserMenu.vue 的 handleLogout() 中检查当前路由是否需要登录，
如果是则 router.push('/') 跳回配方查询页，否则原地 reload。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/LoginModal.vue

@@ -119,7 +119,7 @@ async function submit() {
   position: fixed;
   inset: 0;
   background: rgba(0, 0, 0, 0.35);
-  z-index: 6000;
+  z-index: 5000;
   display: flex;
   align-items: center;
   justify-content: center;

frontend/src/components/UserMenu.vue

@@ -136,7 +136,11 @@ function handleLogout() {
   auth.logout()
   ui.showToast('已退出登录')
   emit('close')
-  window.location.reload()
+  if (router.currentRoute.value.meta.requiresAuth) {
+    router.push('/')
+  } else {
+    window.location.reload()
+  }
 }
 
 onMounted(loadNotifications)

frontend/src/router/index.js

@@ -10,11 +10,13 @@ const routes = [
     path: '/manage',
     name: 'RecipeManager',
     component: () => import('../views/RecipeManager.vue'),
+    meta: { requiresAuth: true },
   },
   {
     path: '/inventory',
     name: 'Inventory',
     component: () => import('../views/Inventory.vue'),
+    meta: { requiresAuth: true },
   },
   {
     path: '/oils',
@@ -25,26 +27,31 @@ const routes = [
     path: '/projects',
     name: 'Projects',
     component: () => import('../views/Projects.vue'),
+    meta: { requiresAuth: true },
   },
   {
     path: '/mydiary',
     name: 'MyDiary',
     component: () => import('../views/MyDiary.vue'),
+    meta: { requiresAuth: true },
   },
   {
     path: '/audit',
     name: 'AuditLog',
     component: () => import('../views/AuditLog.vue'),
+    meta: { requiresAuth: true },
   },
   {
     path: '/bugs',
     name: 'BugTracker',
     component: () => import('../views/BugTracker.vue'),
+    meta: { requiresAuth: true },
   },
   {
     path: '/users',
     name: 'UserManagement',
     component: () => import('../views/UserManagement.vue'),
+    meta: { requiresAuth: true },
   },
 ]