Fix order.page_config → page_config_id in checkout return

The page_config relationship was removed during DB split; use the
page_config_id column and fetch page config via HTTP instead.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cart/bp/cart/global_routes.py

@@ -254,12 +254,15 @@ def register(url_prefix: str) -> Blueprint:
             return await make_response(html)
 
         # Resolve page/market slugs so product links render correctly
-        if order.page_config:
+        if order.page_config_id:
             from shared.infrastructure.data_client import fetch_data
             from shared.contracts.dtos import CalendarEntryDTO, TicketDTO, dto_from_dict
+            raw_pc = await fetch_data("blog", "page-config-by-id",
+                                      params={"id": order.page_config_id},
+                                      required=False)
             post = await fetch_data("blog", "post-by-id",
-                                    params={"id": order.page_config.container_id},
-                                    required=False)
+                                    params={"id": raw_pc["container_id"]},
+                                    required=False) if raw_pc else None
             if post:
                 g.page_slug = post["slug"]
                 result = await g.s.execute(