feat: 后端限速实现 + 前端i18n全面国际化 + 安全与代码质量修复

后端:
- trafficmgr: 实现 tc htb 限速（ApplyRateLimit/RemoveRateLimit），自动推导接口名
- 各协议服务: 代码质量改进与错误处理增强

前端:
- protocols.js: 170个硬编码中文字符串全部转为 i18n key，中英文双语翻译
- 提取 fmtBytes() 到 utils/format.js 公共模块（消除 4 处重复）
- router.js: 添加路由级权限守卫，非管理员无法直接 URL 访问管理页
- Tunnels.vue: SSE 日志流改用 fetch+ReadableStream，token 放 Authorization header
- VPNUsers.vue: 修复 catch 块中文硬编码 fallback
- 新增 TaskProgress 组件、taskmgr 后端任务管理

frontend/src/components/TaskProgress.vue

@@ -0,0 +1,128 @@
+<template>
+  <el-dialog v-model="visible" :title="$t('tunnels.taskProgress')" width="560px" align-center @close="onClose">
+    <div v-if="!task" style="text-align:center;padding:20px;color:var(--text-secondary)">
+      {{ $t('tunnels.noTasks') }}
+    </div>
+    <template v-else>
+      <div style="margin-bottom:16px">
+        <el-tag :type="statusTag" size="small" style="margin-right:8px">{{ statusLabel }}</el-tag>
+        <span style="font-size:13px;color:var(--text-secondary)">
+          {{ task.action === 'start' ? $t('tunnels.batchStart') : task.action === 'stop' ? $t('tunnels.batchStop') : $t('tunnels.batchDelete') }}
+          · {{ task.total }} {{ $t('tunnels.stateTunnel') || 'tunnels' }}
+        </span>
+      </div>
+
+      <el-progress
+        :percentage="progress"
+        :status="task.status === 'done' ? (task.failed > 0 ? 'warning' : 'success') : undefined"
+        :stroke-width="12"
+        style="margin-bottom:16px"
+      />
+
+      <div style="display:flex;gap:16px;margin-bottom:12px;font-size:13px">
+        <span style="color:#67c23a">✓ {{ task.success }}</span>
+        <span style="color:#f56c6c">✗ {{ task.failed }}</span>
+        <span style="color:#909399">⏳ {{ task.total - task.success - task.failed }}</span>
+      </div>
+
+      <el-table :data="task.sub_tasks" size="small" max-height="260">
+        <el-table-column prop="tunnel_name" :label="$t('common.name')" min-width="120" />
+        <el-table-column :label="$t('common.status')" width="100">
+          <template #default="{ row }">
+            <el-tag :type="subTag(row.status)" size="small">{{ subLabel(row.status) }}</el-tag>
+          </template>
+        </el-table-column>
+        <el-table-column prop="error" :label="$t('common.error')" min-width="160">
+          <template #default="{ row }">
+            <span v-if="row.error" style="color:#f56c6c;font-size:12px">{{ row.error }}</span>
+          </template>
+        </el-table-column>
+      </el-table>
+    </template>
+
+    <template #footer>
+      <el-button @click="visible = false">{{ $t('common.close') }}</el-button>
+      <el-button v-if="task?.status !== 'done'" type="primary" @click="refresh">
+        <el-icon v-if="polling" class="is-loading"><Loading /></el-icon>
+        {{ $t('tunnels.refresh') || '刷新' }}
+      </el-button>
+    </template>
+  </el-dialog>
+</template>
+
+<script setup>
+import { ref, computed, watch, onUnmounted } from 'vue'
+import { useI18n } from 'vue-i18n'
+import { Loading } from '@element-plus/icons-vue'
+import api from '../api'
+
+const { t } = useI18n()
+
+const visible = ref(false)
+const task = ref(null)
+const taskId = ref('')
+const polling = ref(false)
+let pollTimer = null
+
+const progress = computed(() => {
+  if (!task.value || task.value.total === 0) return 0
+  return Math.round((task.value.success + task.value.failed) * 100 / task.value.total)
+})
+
+const statusTag = computed(() => {
+  if (!task.value) return 'info'
+  if (task.value.status === 'done') return task.value.failed > 0 ? 'warning' : 'success'
+  return 'primary'
+})
+
+const statusLabel = computed(() => {
+  if (!task.value) return ''
+  if (task.value.status === 'pending') return t('tunnels.taskPending')
+  if (task.value.status === 'running') return t('tunnels.taskInProgress', { done: task.value.success + task.value.failed, total: task.value.total })
+  if (task.value.status === 'done') return task.value.failed > 0 ? t('tunnels.taskPartialFail') : t('tunnels.taskComplete')
+  return task.value.status
+})
+
+function subTag(s) {
+  return { pending: 'info', running: 'primary', done: 'success', failed: 'danger' }[s] || 'info'
+}
+function subLabel(s) {
+  return { pending: t('tunnels.taskPending'), running: t('tunnels.taskRunning'), done: t('tunnels.taskDone'), failed: t('tunnels.taskFailed') }[s] || s
+}
+
+async function open(id) {
+  taskId.value = id
+  visible.value = true
+  await refresh()
+  startPolling()
+}
+
+async function refresh() {
+  try {
+    const { data } = await api.get(`/tasks/${taskId.value}`)
+    task.value = data
+    if (data.status === 'done') stopPolling()
+  } catch { /* task may not exist yet */ }
+}
+
+function startPolling() {
+  stopPolling()
+  polling.value = true
+  pollTimer = setInterval(refresh, 1000)
+}
+
+function stopPolling() {
+  polling.value = false
+  if (pollTimer) { clearInterval(pollTimer); pollTimer = null }
+}
+
+function onClose() {
+  stopPolling()
+  task.value = null
+  taskId.value = ''
+}
+
+onUnmounted(stopPolling)
+
+defineExpose({ open })
+</script>