fix: LEFT JOIN inventory en get_listings para mostrar publicaciones sin vincular

pos/services/marketplace_external_service.py

@@ -588,7 +588,7 @@ def get_listings(tenant_conn, page: int = 1, per_page: int = 50, status: str = N
                l.last_sync_at, l.sync_errors, l.is_active, l.created_at,
                i.part_number, i.name, i.price_1, i.brand
         FROM marketplace_listings l
-        JOIN inventory i ON i.id = l.inventory_id
+        LEFT JOIN inventory i ON i.id = l.inventory_id
         WHERE {' AND '.join(where)}
         ORDER BY l.created_at DESC
         LIMIT %s OFFSET %s