Handle design-time initialization and add a developer debug startup path: App now skips normal startup when in design mode and shows a DevDebugWindow when running in debug (unless a preview or apply-update command). CommandContext.IsDebugMode is extended to include DOTNET_ENVIRONMENT=Development via a new IsDevelopmentEnvironment helper. Program.Main and BuildAvaloniaApp are made public to aid tooling. Added multiple launchSettings profiles for debug and preview commands that set DOTNET_ENVIRONMENT=Development to simplify IDE debugging and UI previewing.
Introduce a per-user OOBE state model and hardened launch/elevation handling. Adds OobeStateFile/OobeLaunchDecision models, OobeStateService (persisting %LOCALAPPDATA%/.launcher/state/oobe-state.json), and LauncherExecutionContext to capture elevation and user SID. CommandContext now normalizes/infers launch-source values (normal, postinstall, apply-update, plugin-install, debug-preview) and exposes maintenance checks. LauncherFlowCoordinator propagates richer launcher context details for diagnostics and suppresses OOBE for elevated/maintenance contexts. PluginInstallerService avoids requesting elevation for user-scoped installs and returns a clear error when installation target is outside the current user's LocalAppData. LauncherClient maps and surfaces result codes, UpdateWorkflow and installer invocation now pass explicit --launch-source values, and WelcomeOobeStep persists OOBE completion via the new service. Adds unit tests (CommandContext, OobeStateService, PluginInstallerService), docs/specs/checklists for the contract, and makes internals visible to tests.
