Refactor application structure: rename 'models' directory to 'db_models', update import paths across multiple files, and enhance Dockerfile to create and populate the new directory, improving organization and clarity in the codebase.

Refactor model structure: update import paths from 'app.modelz' to 'app.models' across multiple files for consistency, remove obsolete 'modelz' directory, and adjust Dockerfile and migration script to reflect these changes, enhancing clarity and organization in the codebase.

Refactor application structure: update model import paths from 'app.model' to 'app.modelz' across multiple files for consistency, and introduce new database models in 'app.modelz.database' to enhance organization and clarity in the codebase.

Refactor imports across application files: update model import paths from 'app.models' to 'app.model' for consistency and clarity, ensuring correct module references throughout the codebase.

Refactor application imports and migration script: update model import paths in env.py and migrate.py, enhance app initialization in __init__.py, and modify PYTHONPATH in run.sh for improved directory structure.

Update Alembic configuration and migration scripts: change script location and version path in alembic.ini, add env.py for migration management, create initial migration script for audiobooks table, and implement migration execution in a new migrate.py script.