Redesign header - move search bar into main navigation

- Move search input with tokens into center of header
- Remove tabs (Search, Catalog, Orders, Seller)
- Icons (bot, globe, user) remain on right side
- Chips for filter selection below input
- Delete GlobalSearchBar.vue and UnifiedSearchBar.vue
- Share searchQuery via useState across composable calls
- Simplify main page to just show hero

app/composables/useCatalogSearch.ts

@@ -216,8 +216,8 @@ export function useCatalogSearch() {
     }
   }
 
-  // Text search (for filtering within current grid)
-  const searchQuery = ref('')
+  // Text search (for filtering within current grid) - shared via useState
+  const searchQuery = useState<string>('catalog-search-query', () => '')
 
   return {
     // State