Unify layouts and create CatalogPage component

- MainNavigation: center tabs on page (absolute positioning)
- SubNavigation: align left instead of center
- Create CatalogPage universal component for list+map pages
- Migrate catalog pages (offers, suppliers, hubs) to CatalogPage
- Remove PageHeader from clientarea pages (redundant with navigation)
- Add topnav layout to supplier detail page

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/components/navigation/SubNavigation.vue

@@ -1,6 +1,6 @@
 <template>
   <nav v-if="items.length > 0" class="bg-base-100 border-b border-base-300">
-    <div class="flex items-center justify-center gap-1 py-2 px-4 overflow-x-auto">
+    <div class="flex items-center gap-1 py-2 px-4 lg:px-6 overflow-x-auto">
       <NuxtLink
         v-for="item in items"
         :key="item.path"