feat: add self-contained structure to remaining modules
Add exceptions, models, schemas, services directories to modules:
customers:
- exceptions.py, models/, schemas/, services/
inventory:
- exceptions.py, models/, schemas/, services/
messaging:
- exceptions.py, models/, schemas/, services/
monitoring:
- exceptions.py, models/, schemas/, services/
orders:
- exceptions.py, models/, schemas/, services/
payments:
- Updated __init__.py
All modules now have the standard self-contained directory
structure ready for future migration of business logic.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>