Extract shared models, services, and application logic into
JdeScoping.ConfigManager.Core library. Add JdeScoping.ConfigManager.Cli
console app with validate, test-connection, and secret commands using
System.CommandLine. UI project now references Core for platform-agnostic
functionality while retaining Avalonia-specific dialog and clipboard services.
Add SecureStore integration to ConfigManager for secure handling of connection
strings and sensitive configuration values. Includes store/secret management
UI, encrypted .store file support, and comprehensive test coverage.