Add configuration for warranty, payment options, and bookkeeping integration

- Defined constants for warranty months, eligibility window, and service months.
- Enabled automatic invoice forwarding to bookkeeping software with email configuration.
- Integrated payment options for Mollie and PayPal, including API keys and webhook settings.
- Disabled pay on delivery option.

index.php

@@ -4,6 +4,21 @@ define('secure_admin_342642', true);
 if (session_status() == PHP_SESSION_NONE) {
     session_start();
 }
+
+//=====================================
+//CHECK USER SESSION
+//=====================================
+if (!isset($_SESSION['loggedin'])) {
+    header('location: login.php');
+    die();
+}
+
+if (isset($_GET['page']) && $_GET['page'] == 'logout') {
+    session_destroy();
+    header('location: login.php');
+    die();
+}
+
 //=====================================
 //INCLUDE CONSTANTS
 //=====================================
@@ -98,21 +113,6 @@ $base_url .= $_SERVER['SERVER_PORT'] == 80 || $_SERVER['SERVER_PORT'] == 443 ||
 $base_url .= '/' . ltrim(substr(str_replace('\\', '/', realpath(__DIR__)), strlen($_SERVER['DOCUMENT_ROOT'])), '/');
 define('base_url', rtrim($base_url, '/') . '/');
 
-
-//=====================================
-//CHECK USER SESSION
-//=====================================
-if (!isset($_SESSION['loggedin'])) {
-    header('location: login.php');
-    die();
-}
-
-if (isset($_GET['page']) && $_GET['page'] == 'logout') {
-    session_destroy();
-    header('location: login.php');
-    die();
-}
-
 //+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 // SIMPLE ROUTING SYSTEM
 //+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++