Split cart into 4 microservices: relations, likes, orders, page-config→blog

Phase 1 - Relations service (internal): owns ContainerRelation, exposes
get-children data + attach/detach-child actions. Retargeted events, blog,
market callers from cart to relations.

Phase 2 - Likes service (internal): unified Like model replaces ProductLike
and PostLike with generic target_type/target_slug/target_id. Exposes
is-liked, liked-slugs, liked-ids data + toggle action.

Phase 3 - PageConfig → blog: moved ownership to blog with direct DB queries,
removed proxy endpoints from cart.

Phase 4 - Orders service (public): owns Order/OrderItem + SumUp checkout
flow. Cart checkout now delegates to orders via create-order action.
Webhook/return routes and reconciliation moved to orders.

Phase 5 - Infrastructure: docker-compose, deploy.sh, Dockerfiles updated
for all 3 new services. Added orders_url helper and factory model imports.

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

blog/services/__init__.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 def register_domain_services() -> None:
     """Register services for the blog app.
 
-    Blog owns: Post, Tag, Author, PostAuthor, PostTag, PostLike.
+    Blog owns: Post, Tag, Author, PostAuthor, PostTag.
     Cross-app calls go over HTTP via call_action() / fetch_data().
     """
     from shared.services.registry import services