fix: scontainers edit saves existing record instead of creating new

Fixes static container admin edit flow by preserving id in hiddenFields and adding route-id fallback during save.
Adds regression tests for edit/create id behavior, updates release docs (changelog/testing/CLAUDE), and appends SonarQube open issues to docs/TODO.

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

autoload/admin/Controllers/ScontainersController.php

@@ -184,8 +184,16 @@ class ScontainersController
         }
 
         $data = $result['data'];
+        $containerId = (int)($data['id'] ?? 0);
+        if ($containerId <= 0) {
+            $routeId = (int)\Shared\Helpers\Helpers::get('id');
+            if ($routeId > 0) {
+                $containerId = $routeId;
+            }
+        }
+
         $savedId = $this->repository->save([
-            'id' => (int)($data['id'] ?? 0),
+            'id' => $containerId,
             'status' => $data['status'] ?? 0,
             'show_title' => $data['show_title'] ?? 0,
             'translations' => $data['translations'] ?? [],
@@ -240,7 +248,6 @@ class ScontainersController
         ];
 
         $fields = [
-            FormField::hidden('id', $id),
             FormField::langSection('translations', 'content', [
                 FormField::text('title', [
                     'label' => 'Tytul',
@@ -283,7 +290,7 @@ class ScontainersController
             $actionUrl,
             '/admin/scontainers/list/',
             true,
-            [],
+            ['id' => $id],
             $languages,
             $errors
         );