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>

lib/Repository/User/BookmarkRepositoryInterface.php

@@ -4,8 +4,11 @@ namespace MintyPHP\Repository\User;
 
 interface BookmarkRepositoryInterface
 {
-    /** @return list<array<string, mixed>> */
-    public function listByUser(int $userId): array;
+    /**
+     * @param array{limit?: int, offset?: int} $options
+     * @return list<array<string, mixed>>
+     */
+    public function listByUser(int $userId, array $options = []): array;
 
     public function nextBookmarkSortOrder(int $userId, ?int $groupId): int;
 
@@ -26,5 +29,8 @@ interface BookmarkRepositoryInterface
     /** @param list<array{id: int, sort_order: int}> $idOrderPairs */
     public function updateSortOrders(int $userId, array $idOrderPairs): bool;
 
-    public function clearGroupId(int $groupId, int $userId): bool;
+    /** @return list<array<string, mixed>> */
+    public function listByGroup(int $userId, int $groupId): array;
+
+    public function unsetGroupId(int $bookmarkId, int $userId, int $sortOrder): bool;
 }