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>

views/templates/front/confirm.tpl

@@ -70,6 +70,17 @@
           <div class="cyp-summary-val">{$form_data.message|escape:'html':'UTF-8'|nl2br nofilter}</div>
         </div>
       {/if}
+      {if isset($withdrawal_deadline) && $withdrawal_deadline != ''}
+        <div class="cyp-summary-row">
+          <div class="cyp-summary-key">{l s='Frist' mod='simple_withdrawalbutton'}</div>
+          <div class="cyp-summary-val" style="color:var(--cyw-accent);font-weight:600;">
+            {l s='bis' mod='simple_withdrawalbutton'} {$withdrawal_deadline|escape:'html':'UTF-8'}
+            <span style="font-size:12px;font-weight:400;color:var(--cyw-text-muted);">
+              ({l s='14 Tage ab Bestelldatum' mod='simple_withdrawalbutton'})
+            </span>
+          </div>
+        </div>
+      {/if}
     </div>
 
     <form method="post" action="{$action_url|escape:'html':'UTF-8'}">

views/templates/front/form.tpl

@@ -28,6 +28,19 @@
       {/if}
     </div>
 
+    {if isset($withdrawal_deadline) && $withdrawal_deadline != ''}
+      <div class="cyp-deadline-notice" style="
+        display:flex; align-items:center; gap:10px; background:#eef2f8;
+        border:1px solid #c5d4eb; border-radius:6px; padding:11px 14px;
+        font-size:13px; color:var(--cyw-accent); margin-bottom:24px;">
+        <span style="font-size:16px;">📅</span>
+        <span>
+          {l s='Widerrufsfrist (14 Tage ab Bestelldatum): bis' mod='simple_withdrawalbutton'}
+          <strong>{$withdrawal_deadline|escape:'html':'UTF-8'}</strong>
+        </span>
+      </div>
+    {/if}
+
     {if $errors_list|@count > 0}
       <div class="alert alert-danger" role="alert">
         <ul>

views/templates/front/success.tpl

@@ -77,6 +77,17 @@
           <div class="cyp-summary-val">{$success_data.message|escape:'html':'UTF-8'|nl2br nofilter}</div>
         </div>
       {/if}
+      {if isset($withdrawal_deadline) && $withdrawal_deadline != ''}
+        <div class="cyp-summary-row">
+          <div class="cyp-summary-key">{l s='Frist' mod='simple_withdrawalbutton'}</div>
+          <div class="cyp-summary-val" style="color:var(--cyw-accent);font-weight:600;">
+            {l s='bis' mod='simple_withdrawalbutton'} {$withdrawal_deadline|escape:'html':'UTF-8'}
+            <span style="font-size:12px;font-weight:400;color:var(--cyw-text-muted);">
+              ({l s='14 Tage ab Bestelldatum' mod='simple_withdrawalbutton'})
+            </span>
+          </div>
+        </div>
+      {/if}
     </div>
 
     <div class="cyp-legal">