feat: initial shared library extraction

Contains shared infrastructure for all coop services:
- shared/ (factory, urls, user_loader, context, internal_api, jinja_setup)
- models/ (User, Order, Calendar, Ticket, Product, Ghost CMS)
- db/ (SQLAlchemy async session, base)
- suma_browser/app/ (csrf, middleware, errors, authz, redis_cacher, payments, filters, utils)
- suma_browser/templates/ (shared base layouts, macros, error pages)
- static/ (CSS, JS, fonts, images)
- alembic/ (database migrations)
- config/ (app-config.yaml)
- editor/ (Lexical editor Node.js build)
- requirements.txt

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

models/user.py

@@ -0,0 +1,46 @@
+from __future__ import annotations
+from datetime import datetime
+from sqlalchemy import String, Integer, DateTime, func, Index, Text, Boolean
+from sqlalchemy.dialects.postgresql import JSONB
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.ext.associationproxy import association_proxy
+from db.base import Base
+
+class User(Base):
+    __tablename__ = "users"
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    email: Mapped[str] = mapped_column(String(255), unique=True, index=True, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
+    last_login_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+
+    # Ghost membership linkage
+    ghost_id: Mapped[str | None] = mapped_column(String(64), unique=True, index=True, nullable=True)
+    name: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    ghost_status: Mapped[str | None] = mapped_column(String(50), nullable=True)  # free, paid, comped
+    ghost_subscribed: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True, server_default=func.true())
+    ghost_note: Mapped[str | None] = mapped_column(Text, nullable=True)
+    avatar_image: Mapped[str | None] = mapped_column(Text, nullable=True)
+    stripe_customer_id: Mapped[str | None] = mapped_column(String(255), index=True, nullable=True)
+    ghost_raw: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
+
+    # Relationships to Ghost-related entities
+
+    user_newsletters = relationship("UserNewsletter", back_populates="user", cascade="all, delete-orphan", lazy="selectin")
+    newsletters = association_proxy("user_newsletters", "newsletter")
+    labels = relationship("GhostLabel", secondary="user_labels", back_populates="users", lazy="selectin")
+    subscriptions = relationship("GhostSubscription", back_populates="user", cascade="all, delete-orphan", lazy="selectin")
+
+    liked_products = relationship("ProductLike", back_populates="user", cascade="all, delete-orphan")
+    liked_posts = relationship("PostLike", back_populates="user", cascade="all, delete-orphan")
+    cart_items = relationship(
+      "CartItem",
+      back_populates="user",
+      cascade="all, delete-orphan",
+    )
+
+    __table_args__ = (
+        Index("ix_user_email", "email", unique=True),
+    )
+
+    def __repr__(self) -> str:
+        return f"<User {self.id} {self.email}>"