- Add CacheHelper for file-based caching with TTL support
- Add Database helper for centralized connection management
- Update WorkflowModel to cache status transitions (10 min TTL)
- Update UserPreferencesModel to cache user prefs (5 min TTL)
- Update manage_workflows.php to clear cache on changes
- Update get_users.php to use Database helper (example migration)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
