Refactor app initialization and migration script: make __init__.py intentionally empty for package structure, and update migrate.py to include project root in Python path for improved module accessibility.

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.

Enhance Dockerfile and application structure: set PYTHONPATH in Dockerfile and run script, add __init__.py to app package, and improve model import error handling in migrations/env.py.