Initial commit: OpenVPN Manager v1.0

OpenVPN Web management console with multi-instance support, client cert
issuance, traffic/connection auditing, certificate expiry reminders,
auto backup/restore.

Stack:
- Backend: Go 1.21+ (Gin + JWT)
- Frontend: Vue 3 + Element Plus + ECharts + Vite
- Storage: JSON file (db.json) + filesystem (pki/, instances/, clients/, backups/)

Features:
- Multi-instance OpenVPN management (independent port/proto/subnet/PKI)
- One-click client certificate issuance with .ovpn (embedded certs)
- Certificate expiry reminders (30-day threshold)
- Connection log parsing (status-version 3)
- Auto backup/restore (tar.gz)
- Audit log for all write operations
- JWT auth (12h TTL)
- One-line install.sh for Ubuntu/Debian/RHEL/Fedora

frontend/src/api/index.js

@@ -0,0 +1,65 @@
+import axios from 'axios'
+import { ElMessage } from 'element-plus'
+import router from '@/router'
+
+const api = axios.create({ baseURL: '/api', timeout: 30000 })
+
+api.interceptors.request.use(cfg => {
+  const t = localStorage.getItem('token')
+  if (t) cfg.headers.Authorization = `Bearer ${t}`
+  return cfg
+})
+
+api.interceptors.response.use(
+  r => r,
+  err => {
+    if (err.response?.status === 401) {
+      localStorage.removeItem('token')
+      if (router.currentRoute.value.path !== '/login') {
+        router.replace('/login')
+      }
+    } else {
+      ElMessage.error(err.response?.data?.error || err.message || '请求失败')
+    }
+    return Promise.reject(err)
+  }
+)
+
+export const Auth = {
+  login: (username, password) => api.post('/login', { username, password }).then(r => r.data),
+  me: () => api.get('/me').then(r => r.data),
+  logout: () => api.post('/logout').then(r => r.data),
+}
+export const Dash = {
+  get: () => api.get('/dashboard').then(r => r.data),
+}
+export const Inst = {
+  list: () => api.get('/instances').then(r => r.data),
+  get: id => api.get(`/instances/${id}`).then(r => r.data),
+  create: data => api.post('/instances', data).then(r => r.data),
+  update: (id, data) => api.put(`/instances/${id}`, data).then(r => r.data),
+  delete: id => api.delete(`/instances/${id}`).then(r => r.data),
+  start: id => api.post(`/instances/${id}/start`).then(r => r.data),
+  stop: id => api.post(`/instances/${id}/stop`).then(r => r.data),
+  online: id => api.get(`/instances/${id}/online`).then(r => r.data),
+  listUsers: id => api.get(`/instances/${id}/users`).then(r => r.data),
+  createUser: (id, data) => api.post(`/instances/${id}/users`, data).then(r => r.data),
+  revokeUser: (id, uid) => api.post(`/instances/${id}/users/${uid}/revoke`).then(r => r.data),
+  deleteUser: (id, uid) => api.delete(`/instances/${id}/users/${uid}`).then(r => r.data),
+  ovpnUrl: (id, uid, host) => `/api/instances/${id}/users/${uid}/ovpn?host=${encodeURIComponent(host||'')}`,
+}
+export const Certs = {
+  list: () => api.get('/certs').then(r => r.data),
+}
+export const Logs = {
+  conns: instanceId => api.get('/connlogs', { params: { instance: instanceId || '' }}).then(r => r.data),
+  audits: () => api.get('/audits').then(r => r.data),
+}
+export const Backup = {
+  list: () => api.get('/backups').then(r => r.data),
+  create: note => api.post('/backups', { note }).then(r => r.data),
+  restore: id => api.post(`/backups/${id}/restore`).then(r => r.data),
+  delete: id => api.delete(`/backups/${id}`).then(r => r.data),
+}
+
+export default api