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>

relations/bp/data/routes.py

@@ -0,0 +1,56 @@
+"""Relations app data endpoints."""
+from __future__ import annotations
+
+from quart import Blueprint, g, jsonify, request
+
+from shared.infrastructure.data_client import DATA_HEADER
+
+
+def register() -> Blueprint:
+    bp = Blueprint("data", __name__, url_prefix="/internal/data")
+
+    @bp.before_request
+    async def _require_data_header():
+        if not request.headers.get(DATA_HEADER):
+            return jsonify({"error": "forbidden"}), 403
+        from shared.infrastructure.internal_auth import validate_internal_request
+        if not validate_internal_request():
+            return jsonify({"error": "forbidden"}), 403
+
+    _handlers: dict[str, object] = {}
+
+    @bp.get("/<query_name>")
+    async def handle_query(query_name: str):
+        handler = _handlers.get(query_name)
+        if handler is None:
+            return jsonify({"error": "unknown query"}), 404
+        result = await handler()
+        return jsonify(result)
+
+    # --- get-children ---
+    async def _get_children():
+        """Return ContainerRelation children for a parent."""
+        from shared.services.relationships import get_children
+
+        parent_type = request.args.get("parent_type", "")
+        parent_id   = request.args.get("parent_id", type=int)
+        child_type  = request.args.get("child_type")
+        if not parent_type or parent_id is None:
+            return []
+        rels = await get_children(g.s, parent_type, parent_id, child_type)
+        return [
+            {
+                "id":          r.id,
+                "parent_type": r.parent_type,
+                "parent_id":   r.parent_id,
+                "child_type":  r.child_type,
+                "child_id":    r.child_id,
+                "sort_order":  r.sort_order,
+                "label":       r.label,
+            }
+            for r in rels
+        ]
+
+    _handlers["get-children"] = _get_children
+
+    return bp