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/httpserver/middleware.go

@@ -0,0 +1,66 @@
+package httpserver
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"github.com/go-chi/chi/v5/middleware"
+	"github.com/google/uuid"
+
+	"github.com/nexavpn/nexavpn/backend/internal/apiutil"
+	"github.com/nexavpn/nexavpn/backend/internal/auth"
+)
+
+type contextKey string
+
+const claimsContextKey contextKey = "claims"
+
+func BaseMiddleware(next http.Handler) http.Handler {
+	return middleware.RealIP(middleware.RequestID(middleware.Logger(next)))
+}
+
+func AuthMiddleware(jwtSecret string) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			header := r.Header.Get("Authorization")
+			if !strings.HasPrefix(header, "Bearer ") {
+				apiutil.Error(w, http.StatusUnauthorized, "unauthorized", "missing bearer token")
+				return
+			}
+
+			claims, err := auth.ParseAccessToken(jwtSecret, strings.TrimPrefix(header, "Bearer "))
+			if err != nil {
+				apiutil.Error(w, http.StatusUnauthorized, "unauthorized", "invalid access token")
+				return
+			}
+
+			ctx := context.WithValue(r.Context(), claimsContextKey, claims)
+			next.ServeHTTP(w, r.WithContext(ctx))
+		})
+	}
+}
+
+func AdminOnly(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		claims, ok := ClaimsFromContext(r.Context())
+		if !ok || claims.Role != "admin" {
+			apiutil.Error(w, http.StatusForbidden, "forbidden", "admin role required")
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+func ClaimsFromContext(ctx context.Context) (auth.Claims, bool) {
+	claims, ok := ctx.Value(claimsContextKey).(auth.Claims)
+	return claims, ok
+}
+
+func MustUserID(ctx context.Context) (uuid.UUID, bool) {
+	claims, ok := ClaimsFromContext(ctx)
+	if !ok {
+		return uuid.Nil, false
+	}
+	return claims.UserID, true
+}