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

backend/internal/profile/builder.go

@@ -0,0 +1,33 @@
+package profile
+
+import (
+	"fmt"
+	"strings"
+)
+
+type BuildInput struct {
+	PrivateKey       string
+	Address          string
+	DNSServers       []string
+	ServerPublicKey  string
+	ServerEndpoint   string
+	AllowedIPs       []string
+	PersistentKeepal int
+}
+
+func BuildWireGuardConfig(input BuildInput) string {
+	var b strings.Builder
+	b.WriteString("[Interface]\n")
+	b.WriteString(fmt.Sprintf("PrivateKey = %s\n", input.PrivateKey))
+	b.WriteString(fmt.Sprintf("Address = %s\n", input.Address))
+	if len(input.DNSServers) > 0 {
+		b.WriteString(fmt.Sprintf("DNS = %s\n", strings.Join(input.DNSServers, ", ")))
+	}
+
+	b.WriteString("\n[Peer]\n")
+	b.WriteString(fmt.Sprintf("PublicKey = %s\n", input.ServerPublicKey))
+	b.WriteString(fmt.Sprintf("Endpoint = %s\n", input.ServerEndpoint))
+	b.WriteString(fmt.Sprintf("AllowedIPs = %s\n", strings.Join(input.AllowedIPs, ", ")))
+	b.WriteString(fmt.Sprintf("PersistentKeepalive = %d\n", input.PersistentKeepal))
+	return b.String()
+}