fix(biji-qianduan): 优化私密笔记和回收站的访问控制

- 移除 HomePage 中重复的私密笔记提示逻辑
- 在 markdown-preview 中通过条件渲染显示私密笔记提示- 为未登录用户提供回收站访问限制
- 新增私密笔记提示内容的单独文件

biji-qianduan/src/components/TrashPage.vue

@@ -1,5 +1,5 @@
 <template>
-  <el-container>
+  <el-container v-if="userStore.isLoggedIn">
     <el-header>
       <h1>回收站</h1>
       <el-button type="danger" @click="handleCleanTrash" :disabled="trashItems.length === 0">清空回收站</el-button>
@@ -26,6 +26,18 @@
       <el-empty v-if="trashItems.length === 0" description="回收站是空的"></el-empty>
     </el-main>
   </el-container>
+  <div v-else class="login-required">
+    <el-result
+      icon="warning"
+      title="需要登录"
+      sub-title="请先登录后再访问回收站"
+    >
+      <template #extra>
+        <el-button type="primary" @click="goToLogin">去登录</el-button>
+        <el-button @click="goBack">返回首页</el-button>
+      </template>
+    </el-result>
+  </div>
 </template>
 
 <script setup>
@@ -33,8 +45,10 @@ import { ref, onMounted } from 'vue';
 import { useRouter } from 'vue-router';
 import { ElMessage, ElMessageBox } from 'element-plus';
 import { getTrash, restoreTrashItem, permanentlyDeleteItem, cleanTrash } from '@/api/CommonApi.js';
+import { useUserStore } from '../stores/user';
 
 const router = useRouter();
+const userStore = useUserStore();
 const trashItems = ref([]);
 
 const fetchTrashItems = async () => {
@@ -86,12 +100,18 @@ const handleCleanTrash = async () => {
   }
 };
 
+const goToLogin = () => {
+  router.push('/login');
+};
+
 const goBack = () => {
   router.push('/home');
 };
 
 onMounted(() => {
-  fetchTrashItems();
+  if (userStore.isLoggedIn) {
+    fetchTrashItems();
+  }
 });
 </script>
 
@@ -101,4 +121,11 @@ onMounted(() => {
   justify-content: space-between;
   align-items: center;
 }
+
+.login-required {
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  height: 100vh;
+}
 </style>