Add CSS hook, URL ref prefill, order prefill, and Widerrufsfrist display

- Fix CSS loading: register stylesheet via actionFrontControllerSetMedia
  hook instead of initContent() — guaranteed to fire before page render
- Upgrade script registers new hook on existing installations
- Feature 1: pre-fill order_reference from ?ref= URL parameter
- Feature 2: pre-fill customer name/email from logged-in account when
  navigating with ?ref= (already worked; now order ref is also pre-filled)
- Feature 4: compute Widerrufsfrist (order date +14 days) from DB and
  display on form (when ref in URL), confirm, and success pages
- Feature 3: EN mail templates were already present

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

simple_withdrawalbutton.php

@@ -50,6 +50,7 @@ class Simple_withdrawalbutton extends Module
             && $this->installTab()
             && $this->registerHook('displayFooter')
             && $this->registerHook('displayCustomerAccount')
+            && $this->registerHook('actionFrontControllerSetMedia')
             && Configuration::updateValue(self::CONF_SHOP_EMAIL, (string) Configuration::get('PS_SHOP_EMAIL'))
             && Configuration::updateValue(self::CONF_RATE_LIMIT, '5')
             && Configuration::updateValue(self::CONF_PRIVACY_URL, '')
@@ -295,6 +296,20 @@ class Simple_withdrawalbutton extends Module
         return $this->display(__FILE__, 'views/templates/hook/customer_account.tpl');
     }
 
+    public function hookActionFrontControllerSetMedia()
+    {
+        if (
+            Tools::getValue('module') === $this->name
+            && Tools::getValue('controller') === 'withdraw'
+        ) {
+            $this->context->controller->registerStylesheet(
+                'cyp-withdrawal',
+                'modules/' . $this->name . '/views/css/withdrawal.css',
+                ['media' => 'all', 'priority' => 200]
+            );
+        }
+    }
+
     public function getWithdrawalLink()
     {
         return $this->context->link->getModuleLink($this->name, 'withdraw', [], true);
@@ -342,6 +357,43 @@ class Simple_withdrawalbutton extends Module
         return $idOrder > 0 ? $idOrder : null;
     }
 
+    public function lookupOrderInfoByReference($orderReference)
+    {
+        $orderReference = $this->cleanText($orderReference, 64);
+        if ($orderReference === '') {
+            return null;
+        }
+
+        $sql = 'SELECT `id_order`, `date_add`, `id_customer`
+            FROM `' . _DB_PREFIX_ . 'orders`
+            WHERE `reference` = "' . pSQL($orderReference) . '"
+            AND `id_shop` = ' . (int) $this->context->shop->id . '
+            ORDER BY `id_order` DESC';
+
+        $row = Db::getInstance()->getRow($sql);
+        if (!$row) {
+            return null;
+        }
+
+        return [
+            'id_order' => (int) $row['id_order'],
+            'date_add' => $row['date_add'],
+            'id_customer' => (int) $row['id_customer'],
+        ];
+    }
+
+    public function computeWithdrawalDeadline($orderDateAdd, $isoCode = 'de')
+    {
+        $timestamp = strtotime((string) $orderDateAdd);
+        if (!$timestamp) {
+            return null;
+        }
+
+        $deadline = strtotime('+14 days', $timestamp);
+
+        return ($isoCode === 'de') ? date('d.m.Y', $deadline) : date('d/m/Y', $deadline);
+    }
+
     public function hashForPrivacy($value)
     {
         $value = trim((string) $value);