Remove empty placeholder modules

[FriggemannMichael]

Summary

Removes empty Django placeholder modules that only contained generated comments and were not imported by the application.

Validation

• python manage.py check
• python manage.py makemigrations --check --dry-run
• pytest -q twice, both runs passing with 179 passed
• ruff check --no-cache on all non-migration project Python files
• Django production import smoke test with django.setup(), admin autodiscovery, and core.urls import

Notes

offers_app/admin.py was intentionally kept because it registers models and is covered by existing tests.