feat(playback): loudness bind rules, analysis seeding, and normalization UI

Resolve integrated loudness from SQLite only at decode bind; keep pre-trim
until a row exists, then allow provisional gain from live updates. Pass
DB-stable hints from the web app into play and gapless preload.

Default pre-measurement attenuation -4.5 dB with an icon reset in Settings;
drop redundant normalization copy and shorten pre-trim descriptions.

analysis_cache seed_from_bytes returns an outcome and skips redundant
waveform work on cache hits; wire callers and related frontend/backend glue.

src/locales/de.ts

@@ -847,6 +847,12 @@ export const deTranslation = {
     replayGainAlbum: 'Album',
     replayGainPreGain: 'Pre-Gain (getaggte Dateien)',
     replayGainFallback: 'Fallback (ohne Tags / Radio)',
+    normalization: 'Normalisierung',
+    loudnessTargetLufs: 'Ziel-LUFS',
+    loudnessPreAnalysisAttenuation: 'Dämpfung vor Messung (dB)',
+    loudnessPreAnalysisAttenuationDesc:
+      'Zusätzliche Dämpfung, bis die Loudness des Titels gespeichert ist. Beim Streamen folgen nur grobe Schätzungen, keine volle Messung. 0 dB = aus; negativer = leiser.',
+    loudnessPreAnalysisAttenuationReset: 'Standard',
     crossfade: 'Crossfade',
     crossfadeDesc: 'Überblendung zwischen Tracks',
     crossfadeSecs: '{{n}} s',

src/locales/en.ts

@@ -853,6 +853,12 @@ export const enTranslation = {
     replayGainAlbum: 'Album',
     replayGainPreGain: 'Pre-Gain (tagged files)',
     replayGainFallback: 'Fallback (untagged / radio)',
+    normalization: 'Normalization',
+    loudnessTargetLufs: 'Target LUFS',
+    loudnessPreAnalysisAttenuation: 'Trim before measurement (dB)',
+    loudnessPreAnalysisAttenuationDesc:
+      'Extra quieting until loudness for this track is saved. Streaming then uses rough guesses, not a full measurement. 0 dB = off; lower = quieter.',
+    loudnessPreAnalysisAttenuationReset: 'Reset to default',
     crossfade: 'Crossfade',
     crossfadeDesc: 'Fade between tracks',
     crossfadeSecs: '{{n}} s',

src/locales/es.ts

@@ -840,6 +840,12 @@ export const esTranslation = {
     replayGainAlbum: 'Álbum',
     replayGainPreGain: 'Pre-Ganancia (archivos etiquetados)',
     replayGainFallback: 'Respaldo (sin etiquetar / radio)',
+    normalization: 'Normalización',
+    loudnessTargetLufs: 'LUFS objetivo',
+    loudnessPreAnalysisAttenuation: 'Atenuación antes de medir (dB)',
+    loudnessPreAnalysisAttenuationDesc:
+      'Atenúa hasta que la loudness del tema esté guardada. En streaming luego solo hay estimaciones aproximadas. 0 dB = ninguna; más negativo = más bajo.',
+    loudnessPreAnalysisAttenuationReset: 'Predeterminado',
     crossfade: 'Crossfade',
     crossfadeDesc: 'Transición entre pistas',
     crossfadeSecs: '{{n}} s',

src/locales/fr.ts

@@ -835,6 +835,12 @@ export const frTranslation = {
     replayGainAlbum: 'Album',
     replayGainPreGain: 'Pré-Gain (fichiers taggés)',
     replayGainFallback: 'Repli (sans tags / radio)',
+    normalization: 'Normalisation',
+    loudnessTargetLufs: 'LUFS cible',
+    loudnessPreAnalysisAttenuation: 'Atténuation avant mesure (dB)',
+    loudnessPreAnalysisAttenuationDesc:
+      'Réduit le volume tant que la loudness du morceau n’est pas enregistrée. En streaming, des estimations grossières suivent, pas une mesure complète. 0 dB = rien ; plus négatif = plus discret.',
+    loudnessPreAnalysisAttenuationReset: 'Valeur par défaut',
     crossfade: 'Fondu enchaîné',
     crossfadeDesc: 'Fondu entre les pistes',
     crossfadeSecs: '{{n}} s',

src/locales/nb.ts

@@ -834,6 +834,12 @@ export const nbTranslation = {
     replayGainAlbum: 'Album',
     replayGainPreGain: 'Pre-Gain (taggede filer)',
     replayGainFallback: 'Reserveverdi (uten tagger / radio)',
+    normalization: 'Normalisering',
+    loudnessTargetLufs: 'Mål-LUFS',
+    loudnessPreAnalysisAttenuation: 'Demping før måling (dB)',
+    loudnessPreAnalysisAttenuationDesc:
+      'Ekstra demping til loudness for sporet er lagret. Streaming bruker deretter grove anslag, ikke full måling. 0 dB = av; lavere = roligere.',
+    loudnessPreAnalysisAttenuationReset: 'Standard',
     crossfade: 'Crossfade',
     crossfadeDesc: 'Tone mellom spor',
     crossfadeSecs: '{{n}}s',

src/locales/nl.ts

@@ -834,6 +834,12 @@ export const nlTranslation = {
     replayGainAlbum: 'Album',
     replayGainPreGain: 'Pre-Gain (getagde bestanden)',
     replayGainFallback: 'Terugval (zonder tags / radio)',
+    normalization: 'Normalisatie',
+    loudnessTargetLufs: 'Doel-LUFS',
+    loudnessPreAnalysisAttenuation: 'Demping vóór meting (dB)',
+    loudnessPreAnalysisAttenuationDesc:
+      'Extra zachter tot de loudness van het nummer is opgeslagen. Streamen gebruikt daarna grove schattingen, geen volledige meting. 0 dB = uit; negatiever = zachter.',
+    loudnessPreAnalysisAttenuationReset: 'Standaard',
     crossfade: 'Overgang',
     crossfadeDesc: 'Fade tussen nummers',
     crossfadeSecs: '{{n}} s',

src/locales/ru.ts

@@ -886,6 +886,12 @@ export const ruTranslation = {
     replayGainAlbum: 'По альбому',
     replayGainPreGain: 'Предусиление (файлы с тегами)',
     replayGainFallback: 'Резерв (без тегов / радио)',
+    normalization: 'Нормализация',
+    loudnessTargetLufs: 'Целевой LUFS',
+    loudnessPreAnalysisAttenuation: 'Ослабление до измерения (dB)',
+    loudnessPreAnalysisAttenuationDesc:
+      'Насколько приглушить звук, пока для трека нет сохранённого измерения громкости. При стриме дальше идут лишь грубые оценки, не полный LUFS. 0 dB — без дополнительного приглушения; ниже — тише.',
+    loudnessPreAnalysisAttenuationReset: 'По умолчанию',
     crossfade: 'Кроссфейд',
     crossfadeDesc: 'Плавный переход между треками',
     crossfadeSecs: '{{n}} с',

src/locales/zh.ts

@@ -829,6 +829,12 @@ export const zhTranslation = {
     replayGainAlbum: '专辑',
     replayGainPreGain: '预增益（有标签文件）',
     replayGainFallback: '回退增益（无标签 / 收音机）',
+    normalization: '响度归一化',
+    loudnessTargetLufs: '目标 LUFS',
+    loudnessPreAnalysisAttenuation: '测量前衰减 (dB)',
+    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。',
+    loudnessPreAnalysisAttenuationReset: '恢复默认',
     crossfade: '交叉淡入淡出',
     crossfadeDesc: '曲目间淡入淡出',
     crossfadeSecs: '{{n}} 秒',