Implement unified catalog search with token-based filtering

- Add useCatalogSearch composable for managing unified search state
- Add UnifiedSearchBar component with token chips for filters
- Add CatalogHero component for empty/landing state
- Create grid components for each display mode:
  - CatalogGridProducts, CatalogGridSuppliers, CatalogGridHubs
  - CatalogGridHubsForProduct, CatalogGridProductsFromSupplier
  - CatalogGridProductsInHub, CatalogGridOffers
- Add unified catalog page at /catalog with query params
- Remove SubNavigation from catalog section (kept for other sections)
- Update all links to use new unified catalog paths
- Delete old nested catalog pages (offers/suppliers/hubs flows)
- Add i18n translations for catalog section

app/layouts/topnav.vue

@@ -18,9 +18,9 @@
         @switch-team="switchToTeam"
       />
 
-      <!-- Sub Navigation (section-specific tabs) - hidden on home page -->
+      <!-- Sub Navigation (section-specific tabs) - only for non-catalog sections -->
       <SubNavigation
-        v-if="!isHomePage"
+        v-if="!isHomePage && !isCatalogSection"
         :section="currentSection"
       />
     </div>
@@ -94,22 +94,32 @@ const isHomePage = computed(() => {
   return route.path === '/' || route.path === '/en' || route.path === '/ru'
 })
 
+// Catalog section detection (unified search, no SubNav needed)
+const isCatalogSection = computed(() => {
+  return route.path.startsWith('/catalog') ||
+         route.path.startsWith('/en/catalog') ||
+         route.path.startsWith('/ru/catalog')
+})
+
 // Show search bar only on main page
 const showSearch = computed(() => isHomePage.value)
 
-// Collapsible header logic - only for catalog pages (not home page)
-const canCollapse = computed(() => !isHomePage.value)
+// Collapsible header logic - only for pages with SubNav
+const hasSubNav = computed(() => !isHomePage.value && !isCatalogSection.value)
+const canCollapse = computed(() => hasSubNav.value)
 const isHeaderCollapsed = computed(() => canCollapse.value && isCollapsed.value)
 
-// Header style - transform for smooth slide animation (only on catalog pages)
+// Header style - transform for smooth slide animation (only when SubNav present)
 const headerStyle = computed(() => {
-  if (isHomePage.value) return {}
+  if (!hasSubNav.value) return {}
   return { transform: `translateY(${headerOffset.value}px)` }
 })
 
 // Main content padding-top to compensate for fixed header
+// 64px = MainNav only (home, catalog)
+// 118px = MainNav + SubNav (orders, seller, settings)
 const mainStyle = computed(() => ({
-  paddingTop: isHomePage.value ? '64px' : '118px'
+  paddingTop: (isHomePage.value || isCatalogSection.value) ? '64px' : '118px'
 }))
 
 // Provide collapsed state to child components (CatalogPage needs it for map positioning)