- Add enumerate_devices_by_engine() returning per-engine device lists
without cross-engine dedup so frontend can filter correctly
- API /audio-devices now includes by_engine dict alongside flat list
- Frontend caches per-engine data, filters device dropdown by selected
template's engine_type, refreshes on template change
- Reorder getting-started tutorial: add API docs and accent color steps
- Fix tutorial trigger button focus outline persisting on step 2
- Use accent color variable for tutorial pulse ring animation
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>