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/app/app.go

@@ -0,0 +1,62 @@
+package app
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"github.com/nexavpn/nexavpn/backend/internal/audit"
+	"github.com/nexavpn/nexavpn/backend/internal/auth"
+	"github.com/nexavpn/nexavpn/backend/internal/config"
+	"github.com/nexavpn/nexavpn/backend/internal/db"
+	"github.com/nexavpn/nexavpn/backend/internal/device"
+	"github.com/nexavpn/nexavpn/backend/internal/gateway"
+	"github.com/nexavpn/nexavpn/backend/internal/httpserver"
+	"github.com/nexavpn/nexavpn/backend/internal/ipam"
+	"github.com/nexavpn/nexavpn/backend/internal/policy"
+	"github.com/nexavpn/nexavpn/backend/internal/user"
+)
+
+type App struct {
+	DB     *pgxpool.Pool
+	Router http.Handler
+}
+
+func New(cfg config.Config) (*App, error) {
+	ctx := context.Background()
+
+	pool, err := db.Connect(ctx, cfg.DatabaseURL)
+	if err != nil {
+		return nil, err
+	}
+
+	authRepo := auth.NewPGRepository(pool)
+	authService := auth.NewService(authRepo, cfg.JWTSecret, cfg.JWTIssuer, cfg.AccessTokenTTL, cfg.RefreshTokenTTL)
+
+	userService := user.NewService(user.NewPGRepository(pool))
+	policyService := policy.NewService(policy.NewPGRepository(pool))
+	gatewayService := gateway.NewService(gateway.NewPGRepository(pool))
+	deviceService := device.NewService(device.NewPGRepository(pool), policyService, gatewayService, ipam.NewService())
+	auditService := audit.NewService(audit.NewPGRepository(pool))
+
+	router := httpserver.NewRouter(cfg.JWTSecret, httpserver.Handlers{
+		Auth:    auth.NewHandler(authService, auditService),
+		User:    user.NewHandler(userService, auditService),
+		Device:  device.NewHandler(deviceService, auditService),
+		Policy:  policy.NewHandler(policyService, auditService),
+		Gateway: gateway.NewHandler(gatewayService),
+		Audit:   audit.NewHandler(auditService),
+	})
+
+	return &App{
+		DB:     pool,
+		Router: router,
+	}, nil
+}
+
+func (a *App) Close() {
+	if a.DB != nil {
+		a.DB.Close()
+	}
+}