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

- Replace blog.models import with shared.models equivalent
- Convert market/models/market.py and market_place.py to re-export stubs
- Update shared + glue submodule pointers

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

models/market_place.py

@@ -1,52 +1 @@
-from __future__ import annotations
-
-from datetime import datetime, timezone
-from typing import Optional, List
-
-from sqlalchemy import (
-    Integer, String, Text, DateTime, ForeignKey, Index, func, text,
-)
-from sqlalchemy.orm import Mapped, mapped_column, relationship
-
-from shared.db.base import Base
-
-
-def utcnow() -> datetime:
-    return datetime.now(timezone.utc)
-
-
-class MarketPlace(Base):
-    __tablename__ = "market_places"
-
-    id: Mapped[int] = mapped_column(Integer, primary_key=True)
-    container_type: Mapped[str] = mapped_column(
-        String(32), nullable=False, server_default=text("'page'"),
-    )
-    container_id: Mapped[int] = mapped_column(Integer, nullable=False)
-    name: Mapped[str] = mapped_column(String(255), nullable=False)
-    slug: Mapped[str] = mapped_column(String(255), nullable=False)
-    description: 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(),
-    )
-    deleted_at: Mapped[Optional[datetime]] = mapped_column(
-        DateTime(timezone=True), nullable=True,
-    )
-
-    nav_tops: Mapped[List["NavTop"]] = relationship(
-        "NavTop", back_populates="market",
-    )
-
-    __table_args__ = (
-        Index("ix_market_places_container", "container_type", "container_id"),
-        Index(
-            "ux_market_places_slug_active",
-            func.lower(slug),
-            unique=True,
-            postgresql_where=text("deleted_at IS NULL"),
-        ),
-    )
+from shared.models.market_place import MarketPlace  # noqa: F401