WIP checkpoint: T1: Moderation data model + Alembic migration

backend/app/models/user.py

@@ -1,13 +1,20 @@
 from datetime import date
 from typing import Optional
 
-from sqlalchemy import Column, Integer, String, Boolean, DateTime, Date
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, Date, Enum
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql import func
 
 from app.database import Base
 
 
+class UserRole:
+    """Valid user roles."""
+    USER = "user"
+    MODERATOR = "moderator"
+    ADMIN = "admin"
+
+
 class User(Base):
     __tablename__ = "users"
 
@@ -17,12 +24,29 @@ class User(Base):
     hashed_password = Column(String(255), nullable=False)
     date_of_birth = Column(Date, nullable=True)
     is_active = Column(Boolean, default=True)
+    role = Column(
+        Enum(UserRole.USER, UserRole.MODERATOR, UserRole.ADMIN, name="user_role", create_type=False),
+        nullable=False,
+        default=UserRole.USER,
+    )
+    banned_until = Column(DateTime(timezone=True), nullable=True)
+    suspended_until = Column(DateTime(timezone=True), nullable=True)
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
 
     sessions = relationship("Session", back_populates="user", cascade="all, delete-orphan")
     worlds = relationship("World", back_populates="owner")
     assets = relationship("Asset", back_populates="owner")
+    moderation_actions_given = relationship(
+        "ModerationAction",
+        foreign_keys="ModerationAction.moderator_id",
+        back_populates="moderator",
+    )
+    moderation_actions_received = relationship(
+        "ModerationAction",
+        foreign_keys="ModerationAction.target_user_id",
+        back_populates="target_user",
+    )
 
     @property
     def is_adult(self) -> bool: