- Refactor to 3-step flow: hardware detection, mode selection, root directory
- Add step indicator 'Step N of 3'
- Add HardwareSummaryStep on step 1 with dynamic heading
- Add ModeSelector on step 2 with 'both' pre-selected
- Add Back buttons on steps 2 and 3
- Persist selected mode via updateNexusSettings on wizard completion
- Reset step and mode on wizard close