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>

federation/Dockerfile

@@ -38,6 +38,12 @@ COPY events/__init__.py ./events/__init__.py
 COPY events/models/ ./events/models/
 COPY account/__init__.py ./account/__init__.py
 COPY account/models/ ./account/models/
+COPY relations/__init__.py ./relations/__init__.py
+COPY relations/models/ ./relations/models/
+COPY likes/__init__.py ./likes/__init__.py
+COPY likes/models/ ./likes/models/
+COPY orders/__init__.py ./orders/__init__.py
+COPY orders/models/ ./orders/models/
 
 # ---------- Runtime setup ----------
 COPY federation/entrypoint.sh /usr/local/bin/entrypoint.sh