feat(helpdesk): add delete button on edit page, fix flash notifications

- Edit page: managers see 'Delete handover' button in aside with confirm dialog
- Delete handler: POST action=delete → deleteByIds → redirect to list
- Flash scope set to null (global) so toast shows reliably after redirect
  regardless of locale prefix or query string in URL
- i18n: added Delete handover / Delete this handover? / Handover deleted (de+en)

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

modules/helpdesk/i18n/default_de.json

@@ -595,5 +595,8 @@
   "Create and assign": "Erstellen & zuweisen",
   "Handover created and assigned": "Übergabe erstellt und zugewiesen",
   "No active employees found.": "Keine aktiven Mitarbeiter gefunden.",
-  "Please select an employee to assign": "Bitte wählen Sie einen Mitarbeiter aus"
+  "Please select an employee to assign": "Bitte wählen Sie einen Mitarbeiter aus",
+  "Delete handover": "Übergabe löschen",
+  "Delete this handover?": "Diese Übergabe löschen?",
+  "Handover deleted": "Übergabe gelöscht"
 }

modules/helpdesk/i18n/default_en.json

@@ -595,5 +595,8 @@
   "Create and assign": "Create and assign",
   "Handover created and assigned": "Handover created and assigned",
   "No active employees found.": "No active employees found.",
-  "Please select an employee to assign": "Please select an employee to assign"
+  "Please select an employee to assign": "Please select an employee to assign",
+  "Delete handover": "Delete handover",
+  "Delete this handover?": "Delete this handover?",
+  "Handover deleted": "Handover deleted"
 }

modules/helpdesk/pages/helpdesk/handovers/create().php

@@ -186,7 +186,7 @@ if ($step === $formStep) {
                     $sessionStore->remove($sessionKey);
 
                     $listUrl = lurl('helpdesk/handovers');
-                    Flash::success(t('Handover created and assigned'), $listUrl, 'handover_created');
+                    Flash::success(t('Handover created and assigned'), null, 'handover_created');
                     Router::redirect($listUrl);
                     return;
                 }

modules/helpdesk/pages/helpdesk/handovers/edit($id).php

@@ -61,6 +61,30 @@ if (!is_array($fieldValues)) {
 
 $errorBag = formErrors();
 
+// Handle delete POST
+if ($request->isMethod('POST') && (string) $request->body('action', '') === 'delete') {
+    if (!Session::checkCsrfToken()) {
+        Flash::error(t('Form expired, please try again'), $editTarget, 'csrf_expired');
+        Router::redirect($editTarget);
+        return;
+    }
+
+    if (!$canManage) {
+        Flash::error(t('Only managers can delete handovers'), $closeTarget, 'delete_denied');
+        Router::redirect($closeTarget);
+        return;
+    }
+
+    $deleteResult = $service->deleteByIds($tenantId, [$handoverId], HandoverService::PERMISSION_MANAGE);
+    if ($deleteResult['ok']) {
+        Flash::success(t('Handover deleted'), null, 'handover_deleted');
+    } else {
+        Flash::error($deleteResult['error'] ?? t('Failed to delete handovers'), null, 'delete_failed');
+    }
+    Router::redirect($closeTarget);
+    return;
+}
+
 // Handle submit-for-review POST
 if ($request->isMethod('POST') && (string) $request->body('action', '') === 'submit_for_review') {
     if (!Session::checkCsrfToken()) {

modules/helpdesk/pages/helpdesk/handovers/edit(default).phtml

@@ -201,6 +201,23 @@ $editBasePath = $editBasePath ?? ('helpdesk/handovers/edit/' . ($handover['id']
         </form>
       <?php endif; ?>
 
+      <?php if ($canManage && !$isViewingRevision): ?>
+        <hr>
+        <form method="post">
+          <input type="hidden" name="action" value="delete">
+          <?php \MintyPHP\Session::getCsrfInput(); ?>
+          <button
+            type="submit"
+            class="danger outline small"
+            style="width: 100%;"
+            data-confirm-message="<?php e(t('Delete this handover?')); ?>"
+            data-confirm-variant="danger"
+          >
+            <i class="bi bi-trash3"></i> <?php e(t('Delete handover')); ?>
+          </button>
+        </form>
+      <?php endif; ?>
+
       <hr>
 
       <?php if ($revisions !== []): ?>