Decouple cart: use shared.models for all cross-app imports

- Replace all imports from blog.models, market.models, events.models
  and bare models.* with shared.models equivalents
- Convert cart/models/order.py and page_config.py to re-export stubs
- Update shared + glue submodule pointers

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

models/order.py

@@ -1,114 +1 @@
-from __future__ import annotations
-
-from datetime import datetime
-from typing import Optional, List
-
-from sqlalchemy import Integer, String, DateTime, ForeignKey, Numeric, func, Text
-from sqlalchemy.orm import Mapped, mapped_column, relationship
-
-from shared.db.base import Base
-
-
-class Order(Base):
-    __tablename__ = "orders"
-
-    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
-
-    user_id: Mapped[Optional[int]] = mapped_column(ForeignKey("users.id"), nullable=True)
-    session_id: Mapped[Optional[str]] = mapped_column(String(64), index=True, nullable=True)
-
-    page_config_id: Mapped[Optional[int]] = mapped_column(
-        ForeignKey("page_configs.id", ondelete="SET NULL"),
-        nullable=True,
-        index=True,
-    )
-
-    status: Mapped[str] = mapped_column(
-        String(32),
-        nullable=False,
-        default="pending",
-        server_default="pending",
-    )
-    currency: Mapped[str] = mapped_column(String(16), nullable=False, default="GBP")
-    total_amount: Mapped[float] = mapped_column(Numeric(12, 2), nullable=False)
-
-    # free-form description for the order
-    description: Mapped[Optional[str]] = mapped_column(Text, nullable=True, index=True)
-
-    # SumUp reference string (what we send as checkout_reference)
-    sumup_reference: Mapped[Optional[str]] = mapped_column(
-        String(255),
-        nullable=True,
-        index=True,
-    )
-
-    # SumUp integration fields
-    sumup_checkout_id: Mapped[Optional[str]] = mapped_column(
-        String(128),
-        nullable=True,
-        index=True,
-    )
-    sumup_status: Mapped[Optional[str]] = mapped_column(String(32), nullable=True)
-    sumup_hosted_url: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
-
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True),
-        nullable=False,
-        server_default=func.now(),
-    )
-    updated_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True),
-        nullable=False,
-        server_default=func.now(),
-        onupdate=func.now(),
-    )
-
-    items: Mapped[List["OrderItem"]] = relationship(
-        "OrderItem",
-        back_populates="order",
-        cascade="all, delete-orphan",
-        lazy="selectin",
-    )
-    page_config: Mapped[Optional["PageConfig"]] = relationship(
-        "PageConfig",
-        foreign_keys=[page_config_id],
-        lazy="selectin",
-    )
-
-
-class OrderItem(Base):
-    __tablename__ = "order_items"
-
-    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
-    order_id: Mapped[int] = mapped_column(
-        ForeignKey("orders.id", ondelete="CASCADE"),
-        nullable=False,
-    )
-
-    product_id: Mapped[int] = mapped_column(
-        ForeignKey("products.id"),
-        nullable=False,
-    )
-    product_title: Mapped[Optional[str]] = mapped_column(String(512), nullable=True)
-
-    quantity: Mapped[int] = mapped_column(Integer, nullable=False, default=1)
-    unit_price: Mapped[float] = mapped_column(Numeric(12, 2), nullable=False)
-    currency: Mapped[str] = mapped_column(String(16), nullable=False, default="GBP")
-
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True),
-        nullable=False,
-        server_default=func.now(),
-    )
-
-    order: Mapped["Order"] = relationship(
-        "Order",
-        back_populates="items",
-    )
-
-    # NEW: link each order item to its product
-    product: Mapped["Product"] = relationship(
-        "Product",
-        back_populates="order_items",
-        lazy="selectin",
-    )
+from shared.models.order import Order, OrderItem  # noqa: F401

models/page_config.py

@@ -1,39 +1 @@
-from __future__ import annotations
-
-from datetime import datetime
-from typing import Optional
-
-from sqlalchemy import Integer, String, Text, DateTime, func, JSON, text
-from sqlalchemy.orm import Mapped, mapped_column, relationship
-
-from shared.db.base import Base
-
-
-class PageConfig(Base):
-    __tablename__ = "page_configs"
-
-    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
-
-    container_type: Mapped[str] = mapped_column(
-        String(32), nullable=False, server_default=text("'page'"),
-    )
-    container_id: Mapped[int] = mapped_column(Integer, nullable=False)
-
-    features: Mapped[dict] = mapped_column(
-        JSON, nullable=False, server_default="{}"
-    )
-
-    # Per-page SumUp credentials (NULL until configured)
-    sumup_merchant_code: Mapped[Optional[str]] = mapped_column(String(64), nullable=True)
-    sumup_api_key: Mapped[Optional[str]] = mapped_column(Text(), nullable=True)
-    sumup_checkout_prefix: Mapped[Optional[str]] = mapped_column(String(64), nullable=True)
-
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), nullable=False, server_default=func.now()
-    )
-    updated_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), nullable=False, server_default=func.now()
-    )
-    deleted_at: Mapped[Optional[datetime]] = mapped_column(
-        DateTime(timezone=True), nullable=True
-    )
+from shared.models.page_config import PageConfig  # noqa: F401