604bfe919c
Apply comprehensive fixes from code reviews including: - Extract shared utilities (SqlFormatHelper, CellValueConverter, DbDestinationBase) - Add interface abstractions (IAuthenticationService, IDatabaseMigrator, IMisQueryBuilder) - Implement SecureStore for encrypted secrets storage - Fix error handling with proper HTTP status codes and logging - Optimize double enumeration in DevEtlRegistry - Add DataSync.Dev README for developer onboarding - Extract filter panel base classes to reduce duplication - Update code review docs to mark all issues as fixed