chore: initial project scaffold with admin web, backend, desktop client, and deployment setup

Add monorepo structure for NexaVPN WireGuard control plane including:
- .gitignore for node_modules, build artifacts, and environment files
- README with project overview, monorepo layout, and quick start guide
- Admin web UI with React, Vite, TypeScript, and nginx reverse proxy
- API client with type definitions for users, devices, policies, gateways, and audit logs
- Admin pages for dashboard, users, devices, policies, g

deploy/.env.example

@@ -0,0 +1,14 @@
+POSTGRES_DB=nexavpn
+POSTGRES_USER=nexavpn
+POSTGRES_PASSWORD=change-me
+DATABASE_URL=postgres://nexavpn:change-me@postgres:5432/nexavpn?sslmode=disable
+HTTP_ADDRESS=:8080
+APP_ENV=production
+JWT_SECRET=replace-with-a-long-random-secret
+JWT_ISSUER=nexavpn
+ACCESS_TOKEN_TTL_SECONDS=900
+REFRESH_TOKEN_TTL_SECONDS=2592000
+DEFAULT_DNS_SERVERS=10.20.0.53
+DEFAULT_VPN_CIDR=100.96.0.0/24
+DEFAULT_GATEWAY_ENDPOINT=vpn.example.com:51820
+DEFAULT_GATEWAY_PUBLIC_KEY=replace-me