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/CatalogSuppliersSection.vue

@@ -4,7 +4,7 @@
       <Stack direction="row" align="center" justify="between">
         <Heading :level="2">{{ t('catalogSuppliersSection.header.title') }}</Heading>
         <NuxtLink
-          :to="localePath('/catalog/suppliers')"
+          :to="localePath('/catalog?select=supplier')"
           class="btn btn-sm btn-ghost"
         >
           <span>{{ t('catalogSuppliersSection.actions.view_all') }}</span>