Optimize catalog loading: backend bounds filtering + early returns

- Add bounds (west/south/east/north) parameters to GetNodes query
- Add setBoundsFilter to useCatalogHubs, useCatalogSuppliers, useCatalogProducts
- Replace client-side bounds filtering with backend query
- Add early return to setProductFilter to avoid redundant fetches
- Watch filterByBounds to trigger backend refetch when checkbox changes

app/composables/useCatalogProducts.ts

@@ -99,6 +99,13 @@ export function useCatalogProducts() {
     }
   }
 
+  // Products don't have coordinates directly (they're an aggregation of offers)
+  // Bounds filtering would require a new backend query that filters by offer locations
+  // For now, this is a no-op - products show all regardless of map bounds
+  const setBoundsFilter = (_bounds: { west: number; south: number; east: number; north: number } | null) => {
+    // No-op: products are not filterable by map bounds in current implementation
+  }
+
   return {
     items,
     isLoading,
@@ -110,6 +117,7 @@ export function useCatalogProducts() {
     init,
     setSupplierFilter,
     setHubFilter,
-    clearFilters
+    clearFilters,
+    setBoundsFilter
   }
 }