chore(php): add toc debug logging for guest visibility issue

Temporary debug logging to diagnose why TOC shows for logged users
but not for guests. Logs visibility checks at each layer.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Shared/Infrastructure/Services/PageVisibilityHelper.php

@@ -43,7 +43,15 @@ final class PageVisibilityHelper
         $container = DIContainer::getInstance();
         $useCase = $container->getEvaluateComponentVisibilityUseCase();
 
-        return $useCase->execute($componentName);
+        $result = $useCase->execute($componentName);
+
+        // DEBUG: Log visibility evaluation
+        if ($componentName === 'table-of-contents') {
+            $isLoggedIn = is_user_logged_in();
+            error_log("PageVisibilityHelper DEBUG [{$componentName}] [" . ($isLoggedIn ? "LOGGED" : "GUEST") . "]: result=" . ($result ? "true" : "false"));
+        }
+
+        return $result;
     }
 
     /**