Add ConfigurationValidationRunner with IConfigurationValidator interface for
validating required settings at startup. Includes SecureStore and LDAP validators.
Expand ConfigManager with pipeline editing UI, dialogs, and step editors.
Update documentation with config validation guidance.
Implement deferred code review findings:
- Add IDialogService/IClipboardService interfaces for testable platform operations
- Create AvaloniaDialogService and AvaloniaClipboardService implementations
- Extract dialog strings and file extensions to centralized Constants classes
- Refactor ViewModels to use DI instead of event delegates
- Update tests to use mock services
Set up repository with legacy .NET Framework 4.8 source (OLD/),
new .NET 10 Blazor solution (NEW/), OpenSpec specifications,
documentation, and project configuration.