refactor(ui): consistent outline/fill icons in topbar, remove dropdown chevrons, truncate breadcrumbs

Use Stripe pattern: outline icons by default, filled for active state
(bookmarks bookmarked, notifications unread). Remove chevron arrows
from tenant/user dropdowns. Add max-width with ellipsis to breadcrumb
items to prevent overflow.

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

modules/bookmarks/templates/topbar-bookmark-button.phtml

@@ -41,6 +41,6 @@ if ($currentPath !== '') {
             data-bookmark-existing-name="<?php e(trim((string) ($existing['name'] ?? ''))); ?>"
             data-bookmark-existing-group="<?php e($existing['group_id'] ?? ''); ?>"
         <?php endif; ?>>
-        <i class="bi <?php e($existing ? 'bi-bookmark-check-fill' : 'bi-bookmark-plus'); ?>"></i>
+        <i class="bi <?php e($existing ? 'bi-bookmark-fill' : 'bi-bookmark'); ?>"></i>
     </button>
 </li>