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>

likes/models/__init__.py

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+from .like import Like

likes/models/like.py

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+from datetime import datetime
+from typing import Optional
+
+from sqlalchemy import Integer, String, DateTime, Index, UniqueConstraint, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from shared.db.base import Base
+
+
+class Like(Base):
+    __tablename__ = "likes"
+
+    __table_args__ = (
+        UniqueConstraint("user_id", "target_type", "target_slug",
+                         name="uq_likes_user_type_slug"),
+        UniqueConstraint("user_id", "target_type", "target_id",
+                         name="uq_likes_user_type_id"),
+        Index("ix_likes_target", "target_type", "target_slug"),
+    )
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+
+    user_id: Mapped[int] = mapped_column(Integer, nullable=False, index=True)
+    target_type: Mapped[str] = mapped_column(String(32), nullable=False)
+    target_slug: Mapped[Optional[str]] = mapped_column(String(255), nullable=True)
+    target_id: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
+
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False,
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False,
+    )
+    deleted_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True), nullable=True,
+    )