WIP checkpoint: Scaffold FastAPI backend project structure

backend/app/models/world.py

@@ -0,0 +1,27 @@
+from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey, Enum
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+import enum
+
+from app.database import Base
+
+
+class WorldVisibility(enum.Enum):
+    PUBLIC = "public"
+    PRIVATE = "private"
+    FRIENDS_ONLY = "friends_only"
+
+
+class World(Base):
+    __tablename__ = "worlds"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String(255), nullable=False)
+    description = Column(Text, nullable=True)
+    owner_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    visibility = Column(Enum(WorldVisibility), default=WorldVisibility.PUBLIC)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
+
+    owner = relationship("User", back_populates="worlds")
+    assets = relationship("Asset", back_populates="world", cascade="all, delete-orphan")