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.
Implements Task 18 from phases 7-9 plan. SearchFormViewModel wraps
SearchSection model with properties for MaxResultRows, TimeoutSeconds,
and MaxConcurrentSearches. Includes full test coverage with 7 tests
verifying initialization, two-way binding, change notification, and
null argument handling.