- Create VideoPlatform StrEnum with WHEREBY and JITSI values
- Update rooms.py and meetings.py to use VideoPlatform enum
- Update views/rooms.py and video_platforms/factory.py to use enum values
- Generate new migration with proper server_default='whereby'
- Apply migration successfully with backward compatibility
- Fix linting and formatting issues
Addresses PR feedback point 1: use StrEnum instead of Literal[]