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/utils/migrations/advancedModeMigration.ts

@@ -0,0 +1,57 @@
+import { useAuthStore } from '../../store/authStore';
+import { DEFAULT_ARTIST_SECTIONS, useArtistLayoutStore } from '../../store/artistLayoutStore';
+import { DEFAULT_QUEUE_TOOLBAR_BUTTONS, useQueueToolbarStore } from '../../store/queueToolbarStore';
+import { DEFAULT_PLAYLIST_LAYOUT_ITEMS, usePlaylistLayoutStore } from '../../store/playlistLayoutStore';
+
+const MIGRATION_FLAG = 'psysonic_advanced_mode_migrated';
+const LEGACY_OPEN_KEY = 'psysonic_personalisation_advanced_open';
+
+function arraysEqual<T extends { id: string; visible: boolean }>(a: T[], b: T[]): boolean {
+  if (a.length !== b.length) return false;
+  for (let i = 0; i < a.length; i++) {
+    if (a[i].id !== b[i].id || a[i].visible !== b[i].visible) return false;
+  }
+  return true;
+}
+
+/**
+ * One-time bridge from the v1.46 "Personalisation → Advanced group" (per-tab
+ * collapsible) to the global Advanced Mode toggle. Auto-enables the new toggle
+ * for users who had previously opened the collapsible OR already customised any
+ * of the three sub-sections that now sit behind it. Idempotent via a localStorage
+ * flag — runs at most once per install.
+ */
+export function runAdvancedModeMigration(): void {
+  try {
+    if (localStorage.getItem(MIGRATION_FLAG) === '1') return;
+  } catch {
+    return;
+  }
+
+  const legacyOpen = (() => {
+    try { return localStorage.getItem(LEGACY_OPEN_KEY) === 'true'; } catch { return false; }
+  })();
+  const artistCustomised = !arraysEqual(
+    useArtistLayoutStore.getState().sections,
+    DEFAULT_ARTIST_SECTIONS,
+  );
+  const queueCustomised = !arraysEqual(
+    useQueueToolbarStore.getState().buttons,
+    DEFAULT_QUEUE_TOOLBAR_BUTTONS,
+  );
+  const playlistCustomised = !arraysEqual(
+    usePlaylistLayoutStore.getState().items,
+    DEFAULT_PLAYLIST_LAYOUT_ITEMS,
+  );
+
+  if (legacyOpen || artistCustomised || queueCustomised || playlistCustomised) {
+    useAuthStore.getState().setAdvancedSettingsEnabled(true);
+  }
+
+  try {
+    localStorage.removeItem(LEGACY_OPEN_KEY);
+    localStorage.setItem(MIGRATION_FLAG, '1');
+  } catch {
+    // best effort — next boot retries
+  }
+}