feat(config): add EnvironmentConfig DTO

Signed-off-by: Vitor Mattos <vitor@php.rio>

Author: vitormattos

src/Config/EnvironmentConfig.php

@@ -0,0 +1,34 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreCode coop and contributors
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreCodeCoop\NfsePHP\Config;
+
+/**
+ * Immutable configuration for the NFS-e environment (sandbox vs. production).
+ *
+ * When no custom base URL is supplied the appropriate official endpoint is
+ * selected automatically from the sandboxMode flag:
+ *
+ *   - Production:  https://nfse.fazenda.gov.br/NFS-e/api/v1
+ *   - Sandbox:     https://hml.nfse.fazenda.gov.br/NFS-e/api/v1
+ */
+final readonly class EnvironmentConfig
+{
+    private const BASE_URL_PROD    = 'https://nfse.fazenda.gov.br/NFS-e/api/v1';
+    private const BASE_URL_SANDBOX = 'https://hml.nfse.fazenda.gov.br/NFS-e/api/v1';
+
+    public string $baseUrl;
+
+    public function __construct(
+        public bool $sandboxMode = false,
+        ?string $baseUrl = null,
+    ) {
+        $this->baseUrl = $baseUrl ?? ($sandboxMode
+            ? self::BASE_URL_SANDBOX
+            : self::BASE_URL_PROD);
+    }
+}