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/components/catalog/SupplierCard.vue

@@ -1,7 +1,7 @@
 <template>
   <component
     :is="linkable ? NuxtLink : 'div'"
-    :to="linkable ? localePath(`/catalog/suppliers/${supplier.uuid}`) : undefined"
+    :to="linkable ? localePath(`/catalog?supplier=${supplier.uuid}`) : undefined"
     class="block"
     :class="{ 'cursor-pointer': selectable }"
     @click="selectable && $emit('select')"