Initial commit: AI Dungeon clone (FastAPI backend + React frontend)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KFsGHju9szibJJa2YJcdbg

backend/app/database.py

@@ -0,0 +1,33 @@
+from pathlib import Path
+
+from sqlalchemy import create_engine, event
+from sqlalchemy.orm import DeclarativeBase, sessionmaker
+
+DB_PATH = Path(__file__).resolve().parent.parent / "data.db"
+
+engine = create_engine(
+    f"sqlite:///{DB_PATH}",
+    connect_args={"check_same_thread": False},
+)
+
+
+@event.listens_for(engine, "connect")
+def _enable_sqlite_foreign_keys(dbapi_connection, _record):
+    # SQLite ships with foreign keys OFF per connection; without this every
+    # ondelete=CASCADE/SET NULL in models.py is silently ignored.
+    cursor = dbapi_connection.cursor()
+    cursor.execute("PRAGMA foreign_keys=ON")
+    cursor.close()
+SessionLocal = sessionmaker(bind=engine, autoflush=False, expire_on_commit=False)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()