Fix header toolbar wrapping at narrow widths

Merge the 900px and 768px breakpoints so the header switches to
vertical layout (column) at 900px instead of awkwardly wrapping
toolbar items into two rows.

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

server/src/wled_controller/static/css/layout.css

@@ -506,13 +506,6 @@ h2 {
 }
 
 @media (max-width: 900px) {
-    .header-toolbar {
-        flex-wrap: wrap;
-        gap: 2px;
-    }
-}
-
-@media (max-width: 768px) {
     header {
         flex-direction: column;
         gap: 8px;