add request helper

backend/app/Utils/RequestHelper.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Utils;
+
+use Psr\Http\Message\ServerRequestInterface;
+
+class RequestHelper
+{
+    /**
+     * 获取客户端真实 IP
+     *
+     * 优先级：X-Forwarded-For → X-Real-IP → ServerParams remote_addr
+     */
+    public static function getClientIp(ServerRequestInterface $request): ?string
+    {
+        $forwarded_for = $request->getHeaderLine('X-Forwarded-For');
+        if ($forwarded_for !== '') {
+            $ips = explode(',', $forwarded_for);
+            return trim($ips[0]);
+        }
+
+        $real_ip = $request->getHeaderLine('X-Real-IP');
+        if ($real_ip !== '') {
+            return trim($real_ip);
+        }
+
+        $server_params = $request->getServerParams();
+        return $server_params['remote_addr'] ?? null;
+    }
+}