Introduce the Settings page, reachable from the Discover gear and the
header menu. Two sub-sections backed by the existing UI-agnostic stores.
- Audio panel: backend, output device and sample-rate dropdowns;
toggles for exclusive mode, DAC passthrough, PipeWire force
bit-perfect, gapless, normalization and quality fallback
- Playback panel: autoplay mode, show context icon, remember session
and resume position
- settings.rs controller owns AudioSettingsStore + PlaybackPreferencesStore
at the shared global path; persists changes and applies audio ones to
the live Player (reload_settings, plus reinit_device for routing-
critical changes); a backend switch re-enumerates output devices
- QbzToggle (switch) and QbzSelect (PopupWindow dropdown) primitives,
SettingRow layout helper, chevron-down icon
- SettingsState global, ContentView::settings, settings-bool /
settings-select callbacks wired through the shell
cc
