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

.gitignore

@@ -0,0 +1,11 @@
+node_modules/
+dist/
+build/
+.DS_Store
+.env
+.env.local
+coverage/
+tmp/
+*.log
+desktop-client/src-tauri/target/
+backend/bin/