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>

controllers/front/withdraw.php

@@ -26,12 +26,6 @@ class Simple_withdrawalbuttonWithdrawModuleFrontController extends ModuleFrontCo
     {
         parent::initContent();
 
-        $this->registerStylesheet(
-            'cyp-withdrawal',
-            'modules/' . $this->module->name . '/views/css/withdrawal.css',
-            ['media' => 'all', 'priority' => 200]
-        );
-
         $this->context->smarty->assign([
             'errors_list' => $this->errorsList,
             'form_data' => $this->formData,
@@ -40,6 +34,7 @@ class Simple_withdrawalbuttonWithdrawModuleFrontController extends ModuleFrontCo
             'success_data' => $this->successData,
             'privacy_url' => (string) Configuration::get(Simple_withdrawalbutton::CONF_PRIVACY_URL),
             'revocation_url' => (string) Configuration::get(Simple_withdrawalbutton::CONF_REVOCATION_URL),
+            'withdrawal_deadline' => $this->computeDeadline(),
         ]);
 
         if ($this->currentView === 'confirm') {
@@ -185,16 +180,37 @@ class Simple_withdrawalbuttonWithdrawModuleFrontController extends ModuleFrontCo
             $customerEmail = (string) $this->context->customer->email;
         }
 
+        $orderRef = $this->module->cleanText(Tools::getValue('ref'), 64);
+
         return [
             'customer_name' => $customerName,
             'customer_email' => $customerEmail,
-            'order_reference' => '',
+            'order_reference' => $orderRef,
             'withdrawal_scope' => 'full',
             'withdrawal_items_text' => '',
             'message' => '',
         ];
     }
 
+    private function computeDeadline()
+    {
+        $ref = isset($this->formData['order_reference']) ? $this->formData['order_reference'] : '';
+        if ($ref === '') {
+            $ref = $this->module->cleanText(Tools::getValue('ref'), 64);
+        }
+        if ($ref === '') {
+            return '';
+        }
+
+        $orderInfo = $this->module->lookupOrderInfoByReference($ref);
+        if (!$orderInfo) {
+            return '';
+        }
+
+        $isoCode = Language::getIsoById((int) $this->context->language->id) ?: 'de';
+        return (string) $this->module->computeWithdrawalDeadline($orderInfo['date_add'], $isoCode);
+    }
+
     private function validateData(array $data)
     {
         $errors = [];