feat: 多主机纳管、用户认证、noVNC控制台、深色主题

主要功能:
- 多主机管理: 支持TCP/SSH方式纳管远程KVM主机
- 用户认证: JWT token认证, 默认admin/admin123
- noVNC控制台: 前端集成noVNC, WebSocket代理VNC连接
- 深色主题: 全局Element Plus深色主题覆盖
- 虚拟机操作: 克隆、迁移、XML编辑、快照管理
- 资源监控: CPU/内存/磁盘IO/网络流量实时监控

Bug修复:
- libvirt getInfo()内存单位修正(MiB非KiB)
- 远程主机VNC 0.0.0.0监听地址连接策略修复
- Dashboard定时器内存泄漏修复
- bcrypt版本兼容性修复

frontend/src/views/VMList.vue

@@ -36,7 +36,7 @@
       </el-table-column>
       <el-table-column prop="name" label="名称" min-width="150">
         <template #default="{ row }">
-          <el-link type="primary" @click="$router.push(`/vm/${row.name}`)">{{ row.name }}</el-link>
+          <el-link type="primary" @click="$router.push(`/vm/${row.name}?host_id=${hostId()}`)">{{ row.name }}</el-link>
         </template>
       </el-table-column>
       <el-table-column label="状态" width="100" align="center">
@@ -77,7 +77,7 @@
             <el-button v-if="row.state === 'running'" type="danger" size="small"
               @click="doAction(row.name, 'force_stop')">强制关</el-button>
             <el-button type="primary" size="small"
-              @click="$router.push(`/vm/${row.name}`)">详情</el-button>
+              @click="$router.push(`/vm/${row.name}?host_id=${hostId()}`)">详情</el-button>
             <el-button type="danger" size="small"
               @click="deleteVM(row)">删除</el-button>
           </el-button-group>
@@ -133,10 +133,14 @@
 
 <script setup>
 import { ref, onMounted } from 'vue'
+import { useRoute } from 'vue-router'
 import { ElMessage, ElMessageBox } from 'element-plus'
 import { Plus, Refresh } from '@element-plus/icons-vue'
 import api from '../api'
 
+const route = useRoute()
+const hostId = () => route.query.host_id || 'local'
+
 const loading = ref(false)
 const creating = ref(false)
 const vms = ref([])
@@ -173,7 +177,7 @@ function formatMem(mb) {
 async function loadData() {
   loading.value = true
   try {
-    const data = await api.get('/vm/list')
+    const data = await api.get('/vm/list', { params: { host_id: hostId() } })
     vms.value = data.vms || []
   } catch (e) {}
   loading.value = false
@@ -182,9 +186,9 @@ async function loadData() {
 async function loadOptions() {
   try {
     const [pools, nets, isos] = await Promise.all([
-      api.get('/storage/pools'),
-      api.get('/network/list'),
-      api.get('/storage/isos'),
+      api.get('/storage/pools', { params: { host_id: hostId() } }),
+      api.get('/network/list', { params: { host_id: hostId() } }),
+      api.get('/storage/isos', { params: { host_id: hostId() } }),
     ])
     poolOptions.value = (pools.pools || []).map(p => p.name)
     networkOptions.value = (nets.networks || []).map(n => n.name)
@@ -196,7 +200,7 @@ async function doAction(name, action) {
   const labels = { start: '启动', stop: '关机', force_stop: '强制关机', pause: '暂停', resume: '恢复' }
   try {
     await ElMessageBox.confirm(`确定要${labels[action]}虚拟机 ${name} 吗？`, '确认', { type: 'info' })
-    await api.post(`/vm/action/${name}`, { action })
+    await api.post(`/vm/action/${name}`, { action }, { params: { host_id: hostId() } })
     ElMessage.success(`${labels[action]}操作已发送`)
     setTimeout(loadData, 2000)
   } catch (e) {
@@ -211,7 +215,7 @@ async function createVM() {
   }
   creating.value = true
   try {
-    await api.post('/vm/create', createForm.value)
+    await api.post('/vm/create', createForm.value, { params: { host_id: hostId() } })
     ElMessage.success('虚拟机创建成功')
     showCreateDialog.value = false
     loadData()
@@ -228,7 +232,7 @@ async function deleteVM(row) {
       '危险操作',
       { type: 'error', confirmButtonText: '确定删除', confirmButtonClass: 'el-button--danger' }
     )
-    await api.delete(`/vm/delete/${row.name}`, { params: { force: row.state === 'running' } })
+    await api.delete(`/vm/delete/${row.name}`, { params: { force: row.state === 'running', host_id: hostId() } })
     ElMessage.success('虚拟机已删除')
     loadData()
   } catch (e) {