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>

web/css/components/app-breadcrumb.css

@@ -42,8 +42,17 @@
     pointer-events: none;
   }
 
+  .app-breadcrumb a,
+  .app-breadcrumb [aria-current="page"] {
+    display: inline-block;
+    max-width: 18ch;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+    vertical-align: middle;
+  }
+
   .app-breadcrumb a {
-    display: inline;
     margin: 0;
     padding: 0;
     color: var(--app-muted-color);