fix: address code review findings for bookmark feature (H1–L5)

Fix broken tests (H1), align interface signatures with implementations (H3),
remove dead code (H4), add missing input guard (M1), replace raw $_SESSION
access with SessionStoreInterface (M2), sync update script schema (M4),
use shared getAppBase utility (L2), document fragment stripping (L3),
and apply app- CSS class prefix convention (L5).

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

templates/partials/app-bookmark-dialog.phtml

@@ -1,13 +1,15 @@
 <?php
 
+use MintyPHP\Http\SessionStoreInterface;
 use MintyPHP\Service\Bookmark\BookmarkService;
 
-$bmSessionData = is_array($_SESSION['user_bookmarks'] ?? null) ? $_SESSION['user_bookmarks'] : [];
+$bmSessionData = is_array(app(SessionStoreInterface::class)->get('user_bookmarks')) ? app(SessionStoreInterface::class)->get('user_bookmarks') : [];
 $bmSessionGroups = is_array($bmSessionData['groups'] ?? null) ? $bmSessionData['groups'] : [];
 
 ?>
 <dialog
   data-app-bookmark-dialog
+  data-app-component="bookmark-save"
   data-max-message="<?php e(t('Maximum bookmarks reached')); ?>"
   data-title-create="<?php e(t('Bookmarks')); ?>"
   data-title-edit="<?php e(t('Bookmarks')); ?>"