- Introduced reusable test utilities in `backend/tests/utils` for FSM transitions, HTMX interactions, and common scenarios.
- Added factory functions for creating test submissions, parks, rides, and photo submissions.
- Implemented assertion helpers for verifying state changes, toast notifications, and transition logs.
- Created comprehensive state machine diagrams for all FSM-enabled models in `docs/STATE_DIAGRAMS.md`, detailing states, transitions, and guard conditions.
- Restructure API v1 with improved serializers organization
- Add user deletion requests and moderation queue system
- Implement bulk moderation operations and permissions
- Add user profile enhancements with display names and avatars
- Expand ride and park API endpoints with better filtering
- Add manufacturer API with detailed ride relationships
- Improve authentication flows and error handling
- Update frontend documentation and API specifications
