fix: populate sidebar context for pages using Page with Sidebar template, use block_template_part for footer (v1.0.6)

- ContextBuilder now calls getSidebarData() when page template slug is
  'page-sidebar', fixing empty sidebar on pages with that template
- Added block_template_part() Twig function to TwigService for FSE
  Template Editor compatibility
- Changed footer rendering from include to block_template_part() so
  footer edits in the Template Editor take effect

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

inc/Template/ContextBuilder.php

@@ -69,6 +69,14 @@ class ContextBuilder
             $context['sidebar'] = $this->getSidebarData();
         }
 
+        // Sidebar data for pages/posts using the "Page with Sidebar" template.
+        if (is_page() || is_singular('post')) {
+            $slug = get_page_template_slug();
+            if ($slug === 'page-sidebar') {
+                $context['sidebar'] = $this->getSidebarData();
+            }
+        }
+
         return $context;
     }