Fix HTTP 500 on live after login, unify database config in config.php, sanitize env example, and harden pentest security

includes/auth.php

@@ -3,6 +3,11 @@
  * Authenticatie & Autorisatie Guard voor Fociz
  */
 
+if (basename($_SERVER['SCRIPT_FILENAME'] ?? '') === 'auth.php') {
+    http_response_code(403);
+    exit('Toegang geweigerd.');
+}
+
 require_once __DIR__ . '/../config/database.php';
 require_once __DIR__ . '/totp.php';
 

includes/index.php

@@ -0,0 +1,3 @@
+<?php
+http_response_code(403);
+exit('Toegang geweigerd.');