[eagleoflqj]

Add Debug-only --preview no-xcode and --preview no-simulators launch options so developers can inspect the setup UI on a configured development machine. Reuse the application's existing views and actions; refreshing keeps the chosen scenario, while launching without arguments performs normal discovery.

Enable DEBUG only for Debug builds and compile out preview handling from Release. Add preview usage documentation, focused tests, and a CI step that builds the Debug app and runs the preview tests after the Release checks.

Validation:

• Debug and Release builds and strict Swift formatting checks passed.
• All seven Debug and six Release CTest checks passed, including preview argument parsing, forced missing Xcode, empty device inventory, selected Xcode paths, and toolchain errors.
• Launched the actual Debug app in both preview modes and normal mode. Both forced screens stayed unchanged after clicking Check Again; App Store and Device Hub actions opened the correct applications.
• Verified Release contains neither the preview flags nor PreviewScenario symbols; the localization catalog remains unchanged.