feat: 初始化项目基础架构和核心功能

- 添加项目基础结构：Cargo.toml、.gitignore、设备UID和密钥文件
- 实现前端Vue3项目结构：路由、登录页面、设备管理页面
- 添加核心协议定义(crates/protocol)：设备状态、资产、USB事件等
- 实现客户端监控模块：系统状态收集、资产收集
- 实现服务端基础API和插件系统
- 添加数据库迁移脚本：设备管理、资产跟踪、告警系统等
- 实现前端设备状态展示和基本交互
- 添加使用时长统计和水印功能插件

web/src/views/Layout.vue

@@ -0,0 +1,189 @@
+<template>
+  <el-container class="app-container">
+    <el-aside width="220px" class="sidebar">
+      <div class="logo">
+        <h2>CSM</h2>
+        <span>终端管理系统</span>
+      </div>
+      <el-menu
+        :default-active="currentRoute"
+        router
+        background-color="#1d1e2c"
+        text-color="#a0a3bd"
+        active-text-color="#409eff"
+      >
+        <el-menu-item index="/dashboard">
+          <el-icon><Monitor /></el-icon>
+          <span>仪表盘</span>
+        </el-menu-item>
+        <el-menu-item index="/devices">
+          <el-icon><Platform /></el-icon>
+          <span>设备管理</span>
+        </el-menu-item>
+        <el-menu-item index="/assets">
+          <el-icon><Box /></el-icon>
+          <span>资产管理</span>
+        </el-menu-item>
+        <el-menu-item index="/usb">
+          <el-icon><Connection /></el-icon>
+          <span>U盘管控</span>
+        </el-menu-item>
+        <el-menu-item index="/alerts">
+          <el-icon><Bell /></el-icon>
+          <span>告警中心</span>
+        </el-menu-item>
+
+        <el-sub-menu index="plugins">
+          <template #title>
+            <el-icon><Grid /></el-icon>
+            <span>安全插件</span>
+          </template>
+          <el-menu-item index="/plugins/web-filter">上网拦截</el-menu-item>
+          <el-menu-item index="/plugins/usage-timer">时长记录</el-menu-item>
+          <el-menu-item index="/plugins/software-blocker">软件管控</el-menu-item>
+          <el-menu-item index="/plugins/popup-blocker">弹窗拦截</el-menu-item>
+          <el-menu-item index="/plugins/usb-file-audit">U盘审计</el-menu-item>
+          <el-menu-item index="/plugins/watermark">水印管理</el-menu-item>
+        </el-sub-menu>
+
+        <el-menu-item index="/settings">
+          <el-icon><Setting /></el-icon>
+          <span>系统设置</span>
+        </el-menu-item>
+      </el-menu>
+    </el-aside>
+
+    <el-container>
+      <el-header class="app-header">
+        <div class="header-left">
+          <span class="page-title">{{ pageTitle }}</span>
+        </div>
+        <div class="header-right">
+          <el-badge :value="unreadAlerts" :hidden="unreadAlerts === 0">
+            <el-icon :size="20"><Bell /></el-icon>
+          </el-badge>
+          <el-dropdown>
+            <span class="user-info">
+              {{ username }} <el-icon><ArrowDown /></el-icon>
+            </span>
+            <template #dropdown>
+              <el-dropdown-menu>
+                <el-dropdown-item @click="handleLogout">退出登录</el-dropdown-item>
+              </el-dropdown-menu>
+            </template>
+          </el-dropdown>
+        </div>
+      </el-header>
+
+      <el-main>
+        <router-view />
+      </el-main>
+    </el-container>
+  </el-container>
+</template>
+
+<script setup lang="ts">
+import { computed, ref, onMounted } from 'vue'
+import { useRoute, useRouter } from 'vue-router'
+import {
+  Monitor, Platform, Box, Connection, Bell, Setting, ArrowDown, Grid
+} from '@element-plus/icons-vue'
+import { api } from '@/lib/api'
+
+const route = useRoute()
+const router = useRouter()
+
+const currentRoute = computed(() => route.path)
+const unreadAlerts = ref(0)
+const username = ref('')
+
+function decodeUsername(): string {
+  try {
+    const token = localStorage.getItem('token')
+    if (!token) return ''
+    const payload = JSON.parse(atob(token.split('.')[1]))
+    return payload.username || ''
+  } catch {
+    return ''
+  }
+}
+
+async function fetchUnreadAlerts() {
+  try {
+    const data = await api.get<any>('/api/alerts/records?handled=0&page_size=1')
+    unreadAlerts.value = data.records?.length || 0
+  } catch {
+    // Silently fail
+  }
+}
+
+const pageTitles: Record<string, string> = {
+  '/dashboard': '仪表盘',
+  '/devices': '设备管理',
+  '/assets': '资产管理',
+  '/usb': 'U盘管控',
+  '/alerts': '告警中心',
+  '/settings': '系统设置',
+  '/plugins/web-filter': '上网拦截',
+  '/plugins/usage-timer': '时长记录',
+  '/plugins/software-blocker': '软件管控',
+  '/plugins/popup-blocker': '弹窗拦截',
+  '/plugins/usb-file-audit': 'U盘审计',
+  '/plugins/watermark': '水印管理',
+}
+
+const pageTitle = computed(() => pageTitles[route.path] || '仪表盘')
+
+onMounted(() => {
+  username.value = decodeUsername()
+  fetchUnreadAlerts()
+})
+
+function handleLogout() {
+  localStorage.removeItem('token')
+  localStorage.removeItem('refresh_token')
+  router.push('/login')
+}
+</script>
+
+<style scoped>
+.app-container { height: 100vh; }
+
+.sidebar {
+  background-color: #1d1e2c;
+  overflow-y: auto;
+}
+
+.logo {
+  padding: 20px;
+  text-align: center;
+  color: #fff;
+  border-bottom: 1px solid #2d2e3e;
+}
+.logo h2 { font-size: 24px; margin-bottom: 4px; }
+.logo span { font-size: 12px; color: #a0a3bd; }
+
+.app-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  border-bottom: 1px solid #e4e7ed;
+  background: #fff;
+}
+
+.page-title { font-size: 18px; font-weight: 600; }
+
+.header-right {
+  display: flex;
+  align-items: center;
+  gap: 20px;
+}
+
+.user-info {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+  cursor: pointer;
+  color: #606266;
+}
+</style>