Replaces the global prerelease toggle with per-core prerelease options in both WPF and Avalonia update views, and persists selections via `CheckPreReleaseCoreTypes` in config. Update checks now resolve prerelease mode per selected core (including auto-check flow), and the sing-box max-version lock is removed to allow newer versions.
Move many model classes into new sub-namespaces (ServiceLib.Models.CoreConfigs, ServiceLib.Models.Configs, ServiceLib.Models.Dto, ServiceLib.Models.Entities). Update GlobalUsings in ServiceLib, v2rayN.Desktop, v2rayN and add a tests GlobalUsings file to reference the new namespaces. Adjust static using directives in ClashApiManager and ClashProxiesViewModel to use ServiceLib.Models.Dto. This is a reorganization/rename of files and namespaces with no functional changes.