refactor: 优化权限管理与登录流程，修复细节问题

1.  调整仪表盘图标从DeviceOutlined为MonitorOutlined
2.  新增403无权访问页面与路由配置
3.  完善权限存储与路由守卫逻辑
4.  修复用户信息获取与token持久化问题
5.  补充普通管理员权限初始化与补丁脚本
6.  优化后端用户服务与认证控制器逻辑
7.  调整登录表单交互与请求流程

client/src/views/403.vue

@@ -0,0 +1,81 @@
+<template>
+  <div class="forbidden-container">
+    <div class="forbidden-content">
+      <div class="forbidden-icon">
+        <LockOutlined />
+      </div>
+      <h1 class="forbidden-title">403</h1>
+      <p class="forbidden-desc">抱歉，您没有访问此页面的权限</p>
+      <p class="forbidden-hint">如需访问，请联系管理员分配相应权限</p>
+      <a-button type="primary" @click="goBack">
+        <ArrowLeftOutlined />
+        返回登录
+      </a-button>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { useRouter } from 'vue-router'
+import { LockOutlined, ArrowLeftOutlined } from '@ant-design/icons-vue'
+import { Button } from 'ant-design-vue'
+
+const router = useRouter()
+
+function goBack() {
+	router.push('/login')
+}
+</script>
+
+<style scoped lang="less">
+.forbidden-container {
+  min-height: 100vh;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: #f5f5f5;
+}
+
+.forbidden-content {
+  text-align: center;
+  padding: 60px 40px;
+  background: #fff;
+  border-radius: 12px;
+  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
+}
+
+.forbidden-icon {
+  width: 120px;
+  height: 120px;
+  margin: 0 auto 24px;
+  background: #fff2f0;
+  border-radius: 50%;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+
+  :deep(.anticon) {
+    font-size: 64px;
+    color: #ff4d4f;
+  }
+}
+
+.forbidden-title {
+  font-size: 72px;
+  font-weight: 700;
+  color: #1f1f1f;
+  margin: 0 0 16px 0;
+}
+
+.forbidden-desc {
+  font-size: 16px;
+  color: #666;
+  margin: 0 0 8px 0;
+}
+
+.forbidden-hint {
+  font-size: 14px;
+  color: #999;
+  margin: 0 0 32px 0;
+}
+</style>