Refactor DataLocationResolver to centralize data path resolution (ResolveLauncherDataPath, ResolveDesktopDataPath, ResolveConfigPath, ResolveLauncherLogsPath, ResolveLauncherStatePath) and replace usages of the previous ".launcher" layout with a "Launcher" folder. Update API: LoadConfig/SaveConfig reorganized and ApplyLocationChoice now accepts an optional custom path and migration flag; migration logic updated accordingly. Update dependent services and views (Logger, DeploymentLocator, UpdateEngineService, OobeStateService, StartupAttemptRegistry, LauncherDebugSettingsStore, OobeWindow) to use the new resolver APIs and paths. Add LauncherBackgroundService to load/validate/cache a custom splash background image and wire it into SplashWindow (AXAML/Axaml.cs) with UI placeholders and overlay. Misc: minor cleanup of Oobe/Splash XAML and related code adjustments and logging improvements.
Introduce support for choosing and resolving the application's data root (system user dir vs. portable app folder). Adds DataLocationConfig model, DataLocationResolver (load/save/resolve/migrate), a UI prompt (DataLocationPromptWindow) and an OOBE step (DataLocationOobeStep) to let users pick and optionally migrate existing data. Wire the chosen data root into the launcher flow and host launch plan (forwarded via --data-root and LMD_DATA_ROOT), and add AppDataPathProvider to let runtime services read the effective data root (initialized in Program.Main). Update various services (logging, settings, DB, plugin/market, startup registry, etc.) to use the new provider/resolver and register the config type in the JSON context. This enables portable installs, safe migration, and runtime overrides via CLI or environment variable.
