feat: 用户个人页面展示当前 VPN 连接信息

- handler/vpn.go: 新增 GetMyVpnConnections，返回当前用户的在线
  VPN 连接列表（IP/连接时间）及 max_conns_per_user 上限
- router.go: 注册 GET /api/me/vpn/connections（普通用户可访问）
- ProfileView.vue: 新增"我的 VPN 连接"区块，含 n/max 徽章、
  IPv4/IPv6/连接时间表格，底部提示异常连接请修改密码
- zh.ts/en.ts: 新增 myVpnConnections/noConnections/
  abnormalConnectionHint 国际化

frontend/src/locales/en.ts

@@ -59,6 +59,9 @@ export default {
     enterOldAndNewPassword: 'Please enter current and new password',
     passwordsDoNotMatch: 'The two passwords do not match',
     passwordChangeFailed: 'Failed to change password',
+    myVpnConnections: 'My VPN Connections',
+    noConnections: 'No active connections',
+    abnormalConnectionHint: 'If you notice any abnormal connections, please change your password to disconnect all devices.',
   },
   about: {
     title: 'About LmVPN',

frontend/src/locales/zh.ts

@@ -59,6 +59,9 @@ export default {
     enterOldAndNewPassword: '请填写原密码和新密码',
     passwordsDoNotMatch: '两次输入的新密码不一致',
     passwordChangeFailed: '密码修改失败',
+    myVpnConnections: '我的 VPN 连接',
+    noConnections: '暂无在线连接',
+    abnormalConnectionHint: '如发现异常连接，请修改密码以断开所有设备',
   },
   about: {
     title: '关于 LmVPN',

frontend/src/views/ProfileView.vue

@@ -8,8 +8,29 @@ const authStore = useAuthStore()
 const router = useRouter()
 const { t } = useI18n()
 
+interface VpnConnection {
+  ip: string
+  ip6?: string
+  connected_at: string
+}
+const vpnConnections = ref<VpnConnection[]>([])
+const maxConns = ref(30)
+
+async function fetchVpnConnections() {
+  try {
+    const res = await fetch('/api/me/vpn/connections', {
+      headers: { Authorization: `Bearer ${authStore.token}` },
+    })
+    if (!res.ok) return
+    const data = await res.json()
+    vpnConnections.value = data.connections || []
+    maxConns.value = data.max_conns_per_user || 30
+  } catch {}
+}
+
 onMounted(async () => {
   await authStore.fetchUser()
+  fetchVpnConnections()
 })
 
 const showPasswordModal = ref(false)
@@ -73,6 +94,35 @@ async function handleChangePassword() {
       </div>
     </div>
 
+    <div class="bg-white dark:bg-gray-800 rounded-xl shadow-sm border border-gray-200 dark:border-gray-700 overflow-hidden mb-6">
+      <div class="flex items-center justify-between p-6 pb-4">
+        <h3 class="text-lg font-semibold text-gray-900 dark:text-white">{{ t('profile.myVpnConnections') }}</h3>
+        <span class="px-3 py-1 text-sm font-medium rounded-full" :class="vpnConnections.length > 0 ? 'bg-sky-100 text-sky-700 dark:bg-sky-900/40 dark:text-sky-400' : 'bg-gray-100 text-gray-500 dark:bg-gray-700 dark:text-gray-400'">
+          {{ vpnConnections.length }} / {{ maxConns }}
+        </span>
+      </div>
+      <table class="w-full text-sm">
+        <thead>
+          <tr class="border-b border-gray-200 dark:border-gray-700 bg-gray-50 dark:bg-gray-800/50">
+            <th class="px-6 py-3 text-left font-medium text-gray-500 dark:text-gray-400">{{ t('vpn.ipv4') }}</th>
+            <th class="px-6 py-3 text-left font-medium text-gray-500 dark:text-gray-400">{{ t('vpn.ipv6') }}</th>
+            <th class="px-6 py-3 text-left font-medium text-gray-500 dark:text-gray-400">{{ t('vpn.connectTime') }}</th>
+          </tr>
+        </thead>
+        <tbody>
+          <tr v-if="!vpnConnections.length">
+            <td colspan="3" class="px-6 py-6 text-center text-gray-400">{{ t('profile.noConnections') }}</td>
+          </tr>
+          <tr v-for="(c, i) in vpnConnections" :key="i" class="border-b border-gray-100 dark:border-gray-700/50">
+            <td class="px-6 py-3 text-gray-700 dark:text-gray-300">{{ c.ip }}</td>
+            <td class="px-6 py-3 text-gray-700 dark:text-gray-300">{{ c.ip6 || '-' }}</td>
+            <td class="px-6 py-3 text-gray-500 dark:text-gray-400">{{ c.connected_at }}</td>
+          </tr>
+        </tbody>
+      </table>
+      <p class="text-xs text-gray-400 px-6 py-4">{{ t('profile.abnormalConnectionHint') }}</p>
+    </div>
+
     <button
       class="px-6 py-2.5 rounded-lg font-medium text-white bg-sky-600 hover:bg-sky-700 transition-colors"
       @click="openPasswordModal"