- Create app/db/base.py with SQLAlchemy Base definition
- Create app/db/session.py with database engine and session setup using absolute path /app/storage/db/db.sqlite
- Create app/models/todo.py with Todo model including id, title, description, completed, created_at, updated_at fields
- Create app/schemas/todo.py with Pydantic schemas for TodoCreate, TodoUpdate, and TodoResponse
- Add necessary __init__.py files for proper package structure
