fix(nav): stop Bootstrap .collapse from hiding desktop top bar

Markup used `collapse navbar-collapse`; BS5 hides `.collapse:not(.show)`.
Drop the `.collapse` class in the header shell and force desktop
`.navbar-collapse` to display:flex so menu/CTA/user/search stay visible.

assets/css/frontend/nav/zib-utilities.css

@@ -105,18 +105,27 @@ body.mobile-navbar-show { overflow: hidden; }
   margin: 0 auto;
   width: 100%;
 }
-.navbar-collapse {
-  display: flex;
+/* Beat Bootstrap 5 `.collapse:not(.show){display:none}` if legacy markup still
+   carries both classes. Desktop top bar is always a flex row. */
+.navbar-top .navbar-collapse,
+.navbar.navbar-top .collapse.navbar-collapse {
+  display: flex !important;
   align-items: center;
   flex: 1;
   min-width: 0;
   flex-wrap: nowrap;
+  visibility: visible;
+  height: auto;
+  overflow: visible;
 }
 .navbar-header { display: flex; align-items: center; flex-shrink: 0; }
 .navbar-top .navbar-toggle { display: none; background: none; border: 0; color: inherit; }
 @media (max-width: 767px) {
   .navbar-top .navbar-toggle { display: inline-flex; align-items: center; justify-content: center; width: 40px; height: 40px; }
-  .navbar-collapse { display: none; }
+  .navbar-top .navbar-collapse,
+  .navbar.navbar-top .collapse.navbar-collapse {
+    display: none !important;
+  }
 }
 
 /* Senior submenu full width under fixed header */