Settings — own Audio categories + Queue Settings consolidation (#1130)

* refactor(settings): promote Normalization and Track transitions to own Audio categories

Pull Normalization and Track transitions out of the combined Playback
section into their own top-level SettingsSubSection categories, placed
directly under Audio Output Device. Both follow the established reusable
pattern (SettingsSubSection header + title-less SettingsGroup inside a
single-group settings-card, so the frame-collapse CSS applies).

- New TrackTransitionsBlock extracted from PlaybackBehaviorBlock; the
  latter now holds only the Queue behaviour toggle (slated to move to
  Personalisation).
- NormalizationBlock's SettingsGroup is now title-less; the section
  header and description name it.
- Split the single audio search-index row into three (Normalization /
  Track transitions / Playback) so crossfade/replaygain/lufs keywords
  focus the right section.

* refactor(settings): consolidate Queue Settings under Personalisation, drop Audio Playback section

Combine Queue Display Mode and Queue Toolbar under one 'Queue Settings'
category in the Personalisation tab, and move the Queue behaviour toggle
(preservePlayNextOrder) there from Audio. The now-empty Audio Playback
section is removed.

- New 'Queue Settings' SettingsSubSection holds three titled groups:
  Queue Display Mode, Queue behaviour, and (advanced-only) Queue Toolbar.
  The toolbar group keeps its reset, now via a new optional 'action' slot
  on SettingsGroup (+ .settings-group-title-action CSS).
- Delete PlaybackBehaviorBlock; its single toggle is inlined.
- Search index: drop the audio 'playbackTitle' row; the personalisation
  queue row now points at 'queueSettingsTitle' with merged keywords.
- i18n: add settings.queueSettingsTitle to all 9 locales.

* fix(settings): align queue-toolbar separator label and restore Advanced badge

- QueueToolbarCustomizer: the separator row rendered a 1px rule where other
  rows have a 16px icon, so its label sat shifted left. Reserve the full
  16px icon column (1px rule centred) so the label lines up. (Preexisting.)
- SettingsGroup gains an optional 'advanced' flag rendering the Advanced
  badge; badge + action now share a right-aligned title-end slot
  (.settings-group-title-end), so the badge sits just left of the reset
  button. Restores the Advanced indicator the Queue Toolbar lost when it
  moved from a SettingsSubSection into a group.

* fix(audio): hide the output-device category on macOS instead of showing a notice

Playback is pinned to the system default on macOS, so the picker showed a
notice explaining it does nothing there. Gate the whole Audio Output Device
category out on macOS (`!IS_MACOS` in AudioTab) and drop the now-dead notice
branch + the `audioOutputDeviceMacNotice` string from all 9 locales. The
device-probe hook already short-circuits on macOS, so no work is wasted.

* refactor(settings): box the sidebar customizer groups consistently

The sidebar display toggles sat as a bare div and looked unfinished. Box
them in a SettingsGroup, with the nav-item drag list in a second group.

Render the groups directly in the sub-section content (no settings-card
wrapper) — matching the other Personalisation customizers, which use bare
SettingsGroups. Also drop the settings-card around Queue Settings for the
same reason, so every Personalisation section's boxes share one width and
inset instead of the card-wrapped ones sitting narrower/indented.

* docs(settings): changelog, what's new, and credits for the settings reorg (#1130)

Fold the Audio/Personalisation reorganization into the existing
'Settings — consistent grouped layout' changelog entry (now #1126 + #1130)
and the matching What's New highlight, and add a consolidated settings-
refactor line to the contributor credits.

WHATS_NEW.md

@@ -28,6 +28,7 @@ Within each section, order by **user impact** (most noticeable first) — not PR
 ### Settings — tidier and easier to scan
 
 - Settings are grouped into clear, labelled panels so related options sit together — less hunting around. The **Native Hi-Res Playback** option now explains in plain language what it actually does.
+- **Normalization** and **Track transitions** are now their own sections under **Settings → Audio**, and the queue options (display mode, toolbar, and Play-Next order) are gathered into one **Queue Settings** group under **Personalisation**.
 
 ## Fixed