fix: Resolve WebSocket authentication error, add verifyJWT alias, and implement 20s heartbeat keep-alive for permanent stable connections

backend/app/Core/Security.php

@@ -194,6 +194,14 @@ class Security
         return $payload;
     }
 
+    /**
+     * Alias for verifyJWT for backward compatibility
+     */
+    public static function decodeJwt(string $token)
+    {
+        return self::verifyJWT($token);
+    }
+
     private static function base64UrlEncode(string $data): string
     {
         return rtrim(strtr(base64_encode($data), '+/', '-_'), '=');