feat: 新增 GRE 隧道协议，管理端口调整为 18080

- backend: 新增 GRE 隧道实现（ip tunnel 点对点互联），binmgr 支持 iproute2
- backend: api/identity 调整，各协议 service（gre/ikev2/ipsec/l2tp/openvpn）统一改动
- backend: OpenVPN 认证辅助与用户口令同步逻辑完善
- frontend: 协议图标/向导/编辑器支持 GRE，VPN 用户页重构（234 行）
- frontend: 新增 RouteListInput 路由列表输入组件，Dashboard/Layout 优化
- i18n: 中英文文案同步更新
- test: 新增 binmgr/common/gre 单测，openvpn 测试补充
- docs: README 补充 GRE 说明，默认监听端口 8080 → 18080
- chore: .gitignore 增加 opsx-vpn.previous（构建备份二进制）

frontend/src/components/ProtocolIcon.vue

@@ -33,6 +33,7 @@ const NAMES = computed(() => ({
   ipsec: 'IPSec',
   ikev2: 'IKEv2',
   l2tp: 'L2TP',
+  gre: 'GRE',
   frp: 'FRP',
   openvpn: 'OpenVPN',
   custom: t('protocolIcon.custom'),
@@ -62,6 +63,9 @@ const ICON_PATHS = {
   // L2TP — 手机+信号波（移动设备拨号语义）
   l2tp: 'M7 1C5.9 1 5 1.9 5 3v18c0 1.1.9 2 2 2h10c1.1 0 2-.9 2-2V3c0-1.1-.9-2-2-2H7zm5 19c-.83 0-1.5-.67-1.5-1.5S11.17 17 12 17s1.5.67 1.5 1.5S12.83 20 12 20zm5-4H7V4h10v12z M9.5 6.5l2 2-2 2-1-1 1-1-1-1 1-1z M14.5 6.5l1 1-1 1 1 1-1 1-2-2 2-2z',
 
+  // GRE — two routed sites connected by a tunnel
+  gre: 'M3 4h6v3H6v10h3v3H3V4zm12 0h6v16h-6v-3h3V7h-3V4zM9 10h6v2H9v-2zm0 4h6v2H9v-2z',
+
   // FRP — 隧道+箭头穿透（内网穿透语义）
   frp: 'M3 8h2v8H3V8zm16 0h2v8h-2V8zM7 10h10v4H7v-4zm2 1.5l2 1.5-2 1.5v-3zm6 0v3l-2-1.5 2-1.5z M12 6l3 2H9l3-2zm0 12l-3-2h6l-3 2z',
 

frontend/src/components/RouteListInput.vue

@@ -0,0 +1,44 @@
+<template>
+  <div class="route-list">
+    <el-input v-model="content" type="textarea" :rows="7" resize="vertical"
+      :placeholder="t('protocols.openvpn.fields.push_routes.placeholder')" @blur="validate" />
+    <span v-if="error" class="route-error">{{ error }}</span>
+  </div>
+</template>
+
+<script setup>
+import { ref, watch } from 'vue'
+import { useI18n } from 'vue-i18n'
+
+const props = defineProps({ modelValue: { type: String, default: '' } })
+const emit = defineEmits(['update:modelValue'])
+const { t } = useI18n()
+const content = ref(props.modelValue || '')
+const error = ref('')
+
+watch(() => props.modelValue, value => {
+  if (value !== content.value) content.value = value || ''
+})
+watch(content, value => emit('update:modelValue', value))
+function validRoute(value) {
+  const [ip, prefix] = value.split('/')
+  const parts = ip.split('.')
+  if (parts.length !== 4 || parts.some(part => !/^\d+$/.test(part) || Number(part) > 255)) return false
+  return prefix === undefined || (/^\d+$/.test(prefix) && Number(prefix) >= 0 && Number(prefix) <= 32)
+}
+function validate() {
+  const filled = String(content.value).split('\n').flatMap(line => line.split('#', 1)[0].split(',')).map(item => item.trim()).filter(Boolean)
+  const invalid = filled.find(item => !validRoute(item))
+  error.value = invalid ? t('protocols.openvpn.fields.push_routes.format_error', { route: invalid }) : ''
+  if (!invalid && content.value !== content.value.trim()) {
+    content.value = content.value.trim()
+  }
+  return !invalid
+}
+defineExpose({ validate })
+</script>
+
+<style scoped>
+.route-list { display:grid; gap:8px; width:100%; }
+.route-error { color:var(--el-color-danger); font-size:12px; }
+</style>