fix(loudness): target sync, effective pre-analysis trim, and queue/settings copy (#333)

* fix(loudness): target sync, -14 pre-analysis ref, queue UI, and reseed

- Front: coalesce loudness refresh by target LUFS; replay-gain IPC dedupe keys
  include norm target and effective pre-attenuation so TGT changes apply.
- Rust: placeholder gain before integrated LUFS uses pivot at -14 LUFS; UI gain
  from effective trim; reseed loudness after delete when waveform cache would skip.
- Pre-analysis: store attenuation relative to -14 LUFS; engine and UI use an
  offset for other targets; migrate legacy absolute values on rehydrate.
- Queue/Settings: Loudness/TGT labels vs value buttons; styles; i18n for help.

* fix(i18n): simplify loudness pre-analysis helper copy

Remove reference-target wording from loudness pre-analysis helper text and keep
only the effective adjustment shown for the current LUFS target in all locales.

src/locales/zh.ts

@@ -840,7 +840,8 @@ export const zhTranslation = {
     loudnessTargetLufsDesc: '所有曲目对齐的参考响度。数值越小，输出越响。流媒体服务通常在 -14 LUFS 左右。',
     loudnessPreAnalysisAttenuation: '测量前衰减',
     loudnessPreAnalysisAttenuationDesc:
-      '在曲目响度数据保存前的额外压低。流式阶段之后只是粗略估计，不是完整测量。0 dB 为不压低；更负则更安静。',
+      '在曲目响度数据保存前的额外压低。流式阶段之后只是粗略估计，不是完整测量。0 dB 为不压低；更负则更安静。右侧显示当前目标下的等效 dB。',
+    loudnessPreAnalysisAttenuationRef: '目标 {{tgt}} LUFS 时等效 {{eff}} dB。',
     loudnessPreAnalysisAttenuationReset: '恢复默认',
     loudnessFirstPlayNote:
       '首次播放新曲目时，音量可能在测量过程中略有波动。下一次播放将使用缓存的测量结果，保持稳定。队列中即将播放的曲目通常在上一首播放期间已完成预分析，所以这种情况在实际使用中很少出现。',