chore(playback): remove Preload Next Track setting (#1007)

* chore(playback): remove Preload Next Track setting

The configurable next-track RAM preload duplicated hot cache and is
obsolete now that ranged streaming starts playback sooner. Gapless and
crossfade still use the internal audio_preload backup when hot cache is off.

* docs: add CHANGELOG entry for Preload Next Track removal (PR #1007)

src/locales/zh/settings.ts

@@ -486,15 +486,7 @@ export const settings = {
   trackPreviewLocation_favorites: '收藏中',
   trackPreviewLocation_artist: '艺人热门曲目中',
   trackPreviewLocation_randomMix: 'Random Mix 中',
-  preloadMode: '预加载下一曲目',
-  preloadModeDesc: '何时开始缓冲队列中的下一曲目',
   nextTrackBufferingTitle: '缓冲',
-  preloadHotCacheMutualExclusive: '预加载与热缓存用途相同——两者不能同时启用。启用其中一个会自动禁用另一个。',
-  preloadOff: '关闭',
-  preloadBalanced: '均衡（结束前30秒）',
-  preloadEarly: '提前（播放5秒后）',
-  preloadCustom: '自定义',
-  preloadCustomSeconds: '结束前秒数：{{n}}',
   infiniteQueue: '无限队列',
   infiniteQueueDesc: '队列播完时自动追加随机曲目',
   experimental: '实验性',
@@ -550,7 +542,7 @@ export const settings = {
   analyticsStrategyAdvancedDesc: '更激进的后台扫描。完成后可获得所有歌曲 BPM，并可即时加载响度与波形。',
   analyticsStrategyPriorityTitle: '分析优先级（始终生效）',
   analyticsStrategyPriorityHigh: '1 — 当前播放：优先下载并分析（播放字节、响度回填，或在需要时走 HTTP）。',
-  analyticsStrategyPriorityMiddle: '2 — 即将播放：队列中接下来的约 5 首、预加载下一首以及热缓存邻近曲目——优先从缓存/已下载字节分析，未命中时才做 HTTP 回填。',
+  analyticsStrategyPriorityMiddle: '2 — 即将播放：队列中接下来的约 5 首及热缓存邻近曲目——优先从缓存/已下载字节分析，未命中时才做 HTTP 回填。',
   analyticsStrategyPriorityLow: '3 — 库批处理（仅“激进”）：自动后台队列排在末尾；按水位线（约 3× workers）补充，无需等待队列清空。',
   analyticsStrategyServerLabel: '服务器',
   analyticsStrategyProgressLabel: '分析进度：',