fix(nav): restore publish/VIP hover bridge and fixed CTA size

Close dead zone under 发布 (transparent bridge + ::before plate), fix
VIP cards hidden by wrong .navbar-vip.hover-show selector, keep CTA 34px.

assets/css/frontend/nav/responsive-mega-menu.css

@@ -26,6 +26,9 @@
   gap: 4px;
   flex-shrink: 0;
   margin-left: auto;
+  overflow: visible;
+  position: relative;
+  z-index: 25;
 }
 
 .nav-settings-link,