feat(settings): global Advanced Mode toggle + playlist page layout (#556) (#720)

Adds a per-element visibility toggle for the playlist detail page (Add
Songs, Import CSV, Download ZIP, Cache Offline, Suggestions) and reworks
the way uncommon options are surfaced: instead of a per-tab collapsible
group, a global "Advanced" toggle in the Settings header reveals all
`advanced` sub-sections across every tab and marks each one with a small
badge. Sets the pattern up so any future advanced option lives in its
natural tab, gated by the same switch.

- New `advancedSettingsEnabled` boolean on `authStore`
  (UiAppearance slice, persisted with the rest of the store).
- `SettingsSubSection` gains an `advanced?: boolean` prop. Hidden when
  the toggle is off; renders an "Advanced" pill in the header when on.
- Settings header gets a Toggle-Switch next to the search lupe.
- `PersonalisationTab` flattens — Sidebar + Home stay always visible;
  Artist sections, Queue Toolbar, and the new Playlist layout get
  `advanced` and disappear by default. `PersonalisationAdvancedGroup`
  component + CSS removed.
- New `playlistLayoutStore` (Zustand + persist, items[{id,visible}] +
  rehydrate sanitize) following the queueToolbarStore pattern.
- `PlaylistHero` and `PlaylistSuggestions` gate the four toolbar buttons
  and the suggestions rail on the store directly.
- One-time migration in MainApp on mount: if the user had opened the
  old per-tab Advanced group (`psysonic_personalisation_advanced_open
  === 'true'`) OR already customised any of the three sub-sections,
  Advanced Mode auto-enables on first launch. Idempotent via a
  localStorage flag; legacy key removed afterwards.
- New i18n keys `settings.advancedMode`, `settings.advancedModeTooltip`,
  `settings.advancedBadge`, `settings.playlistLayout*` in all 9 locales.

Reuses kveld9's design from PR #556; not merged because the locale split
landed afterwards. Credited under the existing kveld9 entry in
settingsCredits.ts.

Co-authored-by: Kveld. <kveld912@proton.me>

src/app/MainApp.tsx

@@ -13,6 +13,7 @@ import { useAuthStore } from '../store/authStore';
 import { useGlobalShortcutsStore } from '../store/globalShortcutsStore';
 import { initHotCachePrefetch } from '../hotCachePrefetch';
 import { initMiniPlayerBridgeOnMain } from '../utils/miniPlayerBridge';
+import { runAdvancedModeMigration } from '../utils/migrations/advancedModeMigration';
 import { IS_WINDOWS } from '../utils/platform';
 import TauriEventBridge from './TauriEventBridge';
 import AppShell from './AppShell';
@@ -29,6 +30,10 @@ const Login = lazy(() => import('../pages/Login'));
 export default function MainApp() {
   const [exportPickerOpen, setExportPickerOpen] = useState(false);
 
+  // One-time bridge from the per-tab Advanced group (v1.46) to the global
+  // Advanced Mode toggle. Idempotent — flagged in localStorage.
+  useEffect(() => { runAdvancedModeMigration(); }, []);
+
   // Push playback state to mini window + handle control events.
   useEffect(() => {
     return initMiniPlayerBridgeOnMain();