Fix Django models, views, and admin interface

Fix Django models, views, and admin interface

- Fixed Question, Choice, and Submission model definitions and formatting

- Resolved indentation issues in views.py that caused import errors

- Updated admin.py to properly register all models

- Added submit and show_exam_result view functions

- Added URL patterns for exam submission and results

- Created superuser creation script for easy admin setup

- Updated course detail and exam result templates