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.
Set up repository with legacy .NET Framework 4.8 source (OLD/),
new .NET 10 Blazor solution (NEW/), OpenSpec specifications,
documentation, and project configuration.